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5W-30 vs. 10W-30


JasonA

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Why does my '97 owners manual recommend 10W-30 oil for all temperatures ABOVE 0*F, but 5W-30 oil for all temperatures BELOW 60*F? The chart is inferring that if the temperatures will be hot, that 10W-30 oil should be used instead of 5W-30.

Isn't 5W-30 and 10W-30 oil going to protect the same at all warm temperatures (both are 30 weights when warm)? And 5W oil will get to more engine parts faster than 10W oil when it's cold...so why the recommendation for 10W-30 instead of 5W-30?

Do the 2000+ Northstar engines recommend 5W-30 or 10W-30?

Thanks,

Jason(2001 STS, White Diamond)

"When you turn your car on...does it return the favor?"

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Jason:

I have captured many "oil" posts from our old guru and none of them say diddly about weight except in the context of something like roller cam followers = reduced friction = opportunity to improve fuel economy.

I use the weight molded into the oil filler cap (factory fill) and my '04 says 5W-30.

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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JasonA, You'll get a gajillion opinions on this (like all oil questions).

A major part of the difference is the additive package. That breaks down with use. More additives are needed to get a bigger range of pourability. If you change oil ahead of schedule there should be no problem using either.

If the bearings in you engine wear and open the clearance up you'll want the 10w-30 to maintain oil pressure. Plenty of other people will chime in.

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I think it more less has to do with cam followers change and the fact that 10w-30 has a higher, high temperture tolerance, generally speaking. And since the pre-2000 design had more friction, that equal more heat.

I use 5w-30 in the winter here in buffalo (lots of below 0 days) and 10w-30 in the spring, winter, and fall. Since I've abandoned the 3month/3000miles rule I'll be changeing it less frequintly and based on the OLM. I'm going to follow the OLM this time (or until when I see the oil getting really dingy) and send a sample to Blackstone Labs to see what they say about it. They can tell me all sorts of things from if my engine is eating itself alive to if the additive package was still intact and I could have gone longer.

The Green's Machines

1998 Deville - high mileage, keeps on going, custom cat-back exhaust

2003 Seville - stock low mileage goodness!

2004 Grand Prix GTP CompG - Smaller supercharger pulley, Ported Exhaust Manifolds, Dyno tune, etc

1998 Firebird Formula - 408 LQ9 Stroker motor swap and all sorts of go fast stuff

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EGreen, how does the 10W-30 have more "high temperature tolerance" than 5W-30, given the assumption that both are conventional oils. I know synthetic oils can tolerate more heat than conventional, but I've never heard that 10W-30 has more tolerance than 5W-30.

I've been thinking of using a 0W-30 in our Grand Caravan (it calls for 5W-30) and seeing that Mobil 1 is so cheap in the 5-gallon jugs at Wal-Mart, I've considered that for the next oil change. GASP!!! That would be the first time I've used a synthetic oil in ANYTHING. But I used to use 10W-30 in the van, out of convenience (because the Cadillac also used it), but noticed a difference in cranking speeds, even with our rather moderate winter temperatures here in North Carolina. So I'm considering 0W-30. A posted on the Chrysler Minivan Fan Club boards has used Mobil 1 0W-40 in two of his minivans since new (one's a 2003 and one's a 1998). Hmmm...

But anyway, for the same reason, I'm considering just using 5W-30 year-round in the Cadillac. It gets pretty hot here in the summer, but again, I'm not sure why Cadillac would specify 5W-30 for temperatures only below 60*F. The manual in our Grand Caravan makes more sense to me. It shows both grades of oil, 5W-30 and 10W-30, and indicates 5W-30 for ALL temperatures, and 10W-30 only for temperatures above freezing. That makes sense to me.

Jason(2001 STS, White Diamond)

"When you turn your car on...does it return the favor?"

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To answer the original question, it's not how hot it gets but how cold. They want 5W-30 in it if it's going to be started cold a lot with temperatures under 60 F.

My dealer here (near Philadelphia) puts 5W-30 in all Northstars year-round. I change my oil when the oil life indicator hits 50%, which is about 3,000 miles of short-trip, suburban driving. Lately I've been using a non-dealer mechanic for routine service and he puts 5W-30 synthetic in it. It works for me.

Everybody has their own viewpoint about oil, particularly the refined vs. synthetic debate. I've been running synthetic in everything since 1990 because I consider it inexpensive relative to maintenance because I tend to drive my cars until the wheels fall off (one of them, I put them back on and drove it several more years). What I have heard is that synthetic oil does not produce the deposits on the hot spots in the head or on the valves that refined oil does. Synthetic oil is less likely to produce sludge. Synthetic oil has cleaner breakdown products in what oil does burn in any engine.

Another reason that I use 5W-30 instead of 10W-30 is based on observation of engine behavior. I notice slightly better "snap" or engine response to the throttle, particularly when it is cold, with 5W-30 synthetic. With refined 10W-30, the engine seems dull and sluggish compared to its normal state. 5W-30 refined is better but not as good as 10W-30 synthetic, and 5W-30 synthetic is best. So, I think it's easier on my engine when it's cold and I get a tad more performance out of it when it's hot with 5W-30 synthetic. This is a clear observation, not an opinion. It was more pronounced in my old Quad 4 HO.

I never tried the 0W-30 oil. It's recommended for arctic climates and is very expensive. But, if I ever do, and I notice even better engine response when fully warmed up, I'll use it. Anyone?

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-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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My dealer here (near Philadelphia) puts 5W-30 in all Northstars year-round.

That really answers my question. To my understanding, if 5W-30 is recommended for when it's cold, it could be used in any weather, since it's a 30 weight when warm anyway.

I never tried the 0W-30 oil. It's recommended for arctic climates and is very expensive. But, if I ever do, and I notice even better engine response when fully warmed up, I'll use it. Anyone?

Check your local Wal-Mart. At mine, all weights of Mobil 1, including 0W-30, are the same price. My local AutoZone carries even more weights than Wal-Mart, and there was a negligible difference in price. Different brands were slightly more expensive. The European formula of Castrol Syntec (available in 0W-30 only, sometimes called "German Castrol") is available for about $4.50/qt, similar in price to the Mobil 1 products.

Wal-Mart has the 5-quart jugs of Mobil 1 for about 20 bucks, or $4/qt.

Thanks Jim.

Jason(2001 STS, White Diamond)

"When you turn your car on...does it return the favor?"

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I was just repeating what I was told. I honestly when I swtiched to the 10w-30 Castrol High Mileage from the synthetic blend 5w-30 noticed a much stronger engine. Especially past the 2000RPM mark.

If I remember correctly there was talk about this on the other cadillac forum and it came back that it had alot to do with the roller cam followers. You could use 5w-30 all year round but it would add wear to the engine. Honestly I felt the same as you about once the oil is warm its the same weight. I think it was stated that the 10w-30 being thicker "most of the time" allows it to stay on the parts that need lubrication where as teh 5w-30 will be more like water and coat the internals less. On the post 2000 cars with the new design there was less friction and thus the 5w-30 was suffiecient. Also something about 5w-30 shearing easier versus the 10w-30. I'll see if I can find that thread.

I don't know why cadillac would specify 10w-30 over 5w-30 unless there is a reason, it also states in big bold text NOT to use any other grades or weights.

With that said I'm going to stay with the blend or dino oil simple because the added cost wont really benefit my northstar, I think someone quoted the guru about that too.

The Green's Machines

1998 Deville - high mileage, keeps on going, custom cat-back exhaust

2003 Seville - stock low mileage goodness!

2004 Grand Prix GTP CompG - Smaller supercharger pulley, Ported Exhaust Manifolds, Dyno tune, etc

1998 Firebird Formula - 408 LQ9 Stroker motor swap and all sorts of go fast stuff

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But anyway, for the same reason, I'm considering just using 5W-30 year-round in the Cadillac. It gets pretty hot here in the summer, but again, I'm not sure why Cadillac would specify 5W-30 for temperatures only below 60*F. The manual in our Grand Caravan makes more sense to me. It shows both grades of oil, 5W-30 and 10W-30, and indicates 5W-30 for ALL temperatures, and 10W-30 only for temperatures above freezing. That makes sense to me.

Actually the manual states you can use 5w-30 for below 60/below0 and 10w-30 above 0. 0w-30 for below 0.

The 2000+ manuals show 5w-30 recommended for any temperature and 10w-30 for anything above 0 (just like your van). My guess would be that something indeed did change to warrant that.

Maybe it was a cost thing? Although I don't think 5w-30 costs more than 10w-30. It might also have to do with the switch to synthetic where as the old engines where showing information for dino oil.

I'm gonna dig up the post I mentioned in my above post...then also find my post at BITOG.

EDIT: found my old post, the pre-2000s were tested and speced for 10w-30 dino oil, and used flat tappet lifters. The post 2000 models with the redesign were speced and used witht 5w-30 synthetic and had roller lifters instead. This also aided in the fuel economy and performance remaining virtually the same dispite the new 87 rather than 91 octane requirement (of course this combined with all the other stuff not just alone). Since 10w-30 is generally thicker (even though they are same weight I guess there is high end to 30 and low end) it works better on the older where as the newer design doesn't require it to be as thick.

Guess use whatever is working for you?

The Green's Machines

1998 Deville - high mileage, keeps on going, custom cat-back exhaust

2003 Seville - stock low mileage goodness!

2004 Grand Prix GTP CompG - Smaller supercharger pulley, Ported Exhaust Manifolds, Dyno tune, etc

1998 Firebird Formula - 408 LQ9 Stroker motor swap and all sorts of go fast stuff

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I've been having the same dillema with my '97. I'm friendly with the guys at the local quick-lube, and they do a decent job (I watch the entire time!) My last visit (with the Jeep) they informed me they won't be carrying 10W-30 any longer due to 'lack of demand.'

I'm very hesitant to switch my N* over to 5W-30, since the weather here in Boston during the summer is warm. My car is also garaged all winter, so it'll rarely be cold-soaked in sub-zero temps overnight.

I can't really imagine any 'damage' being done by the 5w-30, but I just feel a whole lot more comfortable using a slightly thicker oil in a car that runs hot and at high-RPMs. Plus, I'd think a thicker oil will be less apt to sneak out from between the seals and end up on the garage floor.

Just my $.02!

-Scott

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My 1997 ETC had a seeping o-ring but never left oil on the garage floor. If you see oil on the garage floor, it's from the oil pan, I would venture, or you have an oil leak that needs a repair such as a truly blown o-ring.

I used 10W-30 synthetic from when I got it new in October 1997 until about 2003, when the dealer started putting 5W-30 in it with my permission. I could tell the difference in engine snap at any RPM and in about 1998 caught the dealer putting in refined oil instead of synthetic by mistake. They changed it again free. One other time this CA dealer caught it before the delivered the car to me and asked if I minded waiting another half hour while they drained it and used synthetic. My real problem with this particular dealer was wiping off the passenger side rear view mirror in the car wash, and taking two hours "to wash the car" while the fixed it.

In my humble opinion, I don't think that engine durability or wear rate is affected by the use of 5W-30 or 10W-30, or refined versus synthetic. You may want to change refined oil sooner and deposits in the cam covers and on the valves may be more likely or thicker with refined oil. But, if it meets GM specifications for your car, differences in wear should be negligible, and a Northstar with 3,000 mile oil changes will go forever.

My engine ran fine and had no drivability issues for 117,000 miles. What did it in was leaving the coolant in for seven years; it got the head gasket. That, and the o-ring seepage, and posts here that the o-ring tended to go at about 130,000 miles, plus an oil burning problem that had started abruptly at about 75,000 miles and seemed to be due to stuck rings, and I added up the bills and decided to just pay one bill. The point here is that synthetic oil seems quite good for engine life.

Thicker oil may reduce oil burning slightly, but that doesn't seem like a reason to use it to me. The engine was clean on tear-down, and I have some rather startling pictures that look like a new engine inside.

I notice better engine snap with synthetic oil, but EGreen says that his 1998 275 hp engine is stronger with 10W-30 Castrol high mileage oil than with 5W-30 blend; he didn't say what brand of blend. Perhaps the 10W-30 Castrol high mileage oil is synthetic with a film additive. But, I don't know why 10W-30 Castrol high mileage gives him a performance improvement over his old oil.

So, in conclusion, it's the owner's choice. I go with 5W-30 synthetic for very slight advantages in fuel economy and performance. I have a hard time equating that observable effect -- more engine snap -- with a higher wear rate. The new-engine look my engine had on teardown at 117,000 miles tells me that 3,000 mile oil changes with synthetic oil keep my engine clean inside. But, I have no really good reason to tell anyone that 10W-30 refined oil is not a good idea, either.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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ALL of you guys are forgetting one or two things. First, we're talking about 1997 oil chemistry, probably BEFORE SL motor oil was even invented. And second, about VII's! In 1997, the only way to make a 5W-30 was to add more Viscosity Index Improvers (VII's), which at that time, were not very good. They were responsible for MANY stuck rings. Cadillac's decision to write the manual in that way DISCOURAGED the use of "wide spread" conventional oils, so 10W-30 was their main choice. And for those that are listening, that includes 15W-40 CI or diesel rated engine oils, regardless of their supposedly higher detergency.

Combine this with flat tappets in the engine, high shear gear pumps for oil delivery, standard gear drive distributors, and you'll see why 10W-30 may be a better choice.

Never underestimate the amount of a persons greed.

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JohnnyG -- none of the Northstars have physical distributors. The distributor is a figament of the imagination of the PCM. I'd been running 5W-30 synthetic in my Quad 4 HO for seven years when I traded it on my 1997 ETC and was surprised that Cadillac recommended 10W-30 instead of 5W-30, as was used in most new engine designs since about 1990.

The owners' manual apparently didn't consider synthetic oils at all. The better viscosity control of synthetics with lower levels of VII's may add a bit of perspective.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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I once asked the Guru about this. As I recall he said that GM went to 5W30 after the roller finger followers (2000+) because the flat tappets were the last thing that prevented them from doing it (shear). I got the distinct impression that it was done to satisfy the EPA and given a choice, they would have stayed with 10W30, which is what I use in all my cars regardless of the 5W30 recommendation.

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^I got that also in response on the BITOG forum. They told me however next time I may want to try the 5w-30 Castrol GTX High Mileage because Castrol is known for its resistance to shear.

As always though I am nervous about doing a switch since this is working (minus a tick at first startup that lasts until I rev it up once, could be because of the oil change or coincidance).

In regard to the oil I switched from, it was a Synthetic Blend, 5w-30 by Kendall. When I first switched to it I noticed a smoother operation and such but that was from a no-name dino oil. They also offer a synthetic blend high mileage but I haven't been able to find the oil in the stores, they seem to sell mostly to just car care centers.

I then in this last change went to the Castrol GTX High Mileage and indeed the car felt much stronger, especially above that 2000 RPM "line" that these babies really start to move. After a bit of driving whatever the addtives did/do I could really feel the car push me back into my seat. I know the butt dino isn't always right but even my father said "hey, this thing stronger than before or is it just me?"

I'll probibly stick to my guns and use the 5w-30 for the cold buffalo winters early morning driving my brother to school in january can register -4 and below, with the wind chill it take the wind out of ya. If the car was garaged I'd stick with the 10w-30 (and just might if we can get some of the crap out of there, 2.5 houses worth of "stuff" cramed into my home sweet home.)

The Green's Machines

1998 Deville - high mileage, keeps on going, custom cat-back exhaust

2003 Seville - stock low mileage goodness!

2004 Grand Prix GTP CompG - Smaller supercharger pulley, Ported Exhaust Manifolds, Dyno tune, etc

1998 Firebird Formula - 408 LQ9 Stroker motor swap and all sorts of go fast stuff

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I think I'm going to probably do what JohnnyG recommended in another thread: stick to the conventional Havoline. That's what's been working for me in the past. 153k miles. No sludge build-up at all. No stuck rings. No carbon rap. No problems. I can eat lunch off my cylinder heads, from the view through the oil fill port, using the OLM as a general indicator (usually change at about 30%).

I've actually used a variety of brands: Valvoline, Pennzoil, and Havoline. I think the High Mileage oils I was using were Pennzoil. I don't think I've ever used the MaxLife (Valvoline). I may try one of those on the next change.

The Havoline is $9 for the 5 qt jug, vice $22 for Mobil 1.

Jason(2001 STS, White Diamond)

"When you turn your car on...does it return the favor?"

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Hello all,

look at the chart which is printed in my '96 german owner's manual, 5W30 is fine for all temperatures.

I can't get 10W30 over here anyway, not on sale.

I bought some gallons of synthetic 5W30 for a very good price recently, and used it on the last oil change. 7,000 kms since and no leaks, bone dry.

And the lifter noise on startup (after more than one day unused) has gone too!

Stefan

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JohnnyG -- none of the Northstars have physical distributors. The distributor is a figament of the imagination of the PCM. I'd been running 5W-30 synthetic in my Quad 4 HO for seven years when I traded it on my 1997 ETC and was surprised that Cadillac recommended 10W-30 instead of 5W-30, as was used in most new engine designs since about 1990.

Yeah, But...what Ranger said......a high performance V8, with 32 flat tappet valves = 10W-30 in my book.

And no, once again according to the Guru, Synthetic was probably NOT considered at all since the engineering team determined that the only real benefit was from high temperature applications...which the Northy is not. (there, I used the term too..) And this appiles most directly to 1997 vintage synthetics..who knows what the state of developement was at that time. The opinion of the engineers contiunues today...otherwise they would be stating "synthetic ONLY" in the owners manual. Now the REAL question is at what point might VII's really come in to play, or reduced VII's of synhetic (theroetically) Since I can't get anyone to state exactly which oil contains exactly WHICH or how much VII.

from egreen: In regard to the oil I switched from, it was a Synthetic Blend, 5w-30 by Kendall. When I first switched to it I noticed a smoother operation and such but that was from a no-name dino oil. They also offer a synthetic blend high mileage but I haven't been able to find the oil in the stores, they seem to sell mostly to just car care centers.

Kendall is only a no-name oil in some parts of the country. I think you'll find it a VERY good oil, especially for the price. Forget about the synthetic blends, you won't need them either. My brother runs a 1990 Ford F150 with the 300 cu. in. straight six......300,000 miles on Kendall and not even the plastic timing gear has worn out!

Never underestimate the amount of a persons greed.

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EGreen, how does the 10W-30 have more "high temperature tolerance" than 5W-30, given the assumption that both are conventional oils. I know synthetic oils can tolerate more heat than conventional, but I've never heard that 10W-30 has more tolerance than 5W-30.

I've been thinking of using a 0W-30 in our Grand Caravan (it calls for 5W-30) and seeing that Mobil 1 is so cheap in the 5-gallon jugs at Wal-Mart, I've considered that for the next oil change. GASP!!! That would be the first time I've used a synthetic oil in ANYTHING. But I used to use 10W-30 in the van, out of convenience (because the Cadillac also used it), but noticed a difference in cranking speeds, even with our rather moderate winter temperatures here in North Carolina. So I'm considering 0W-30. A posted on the Chrysler Minivan Fan Club boards has used Mobil 1 0W-40 in two of his minivans since new (one's a 2003 and one's a 1998). Hmmm...

But anyway, for the same reason, I'm considering just using 5W-30 year-round in the Cadillac. It gets pretty hot here in the summer, but again, I'm not sure why Cadillac would specify 5W-30 for temperatures only below 60*F. The manual in our Grand Caravan makes more sense to me. It shows both grades of oil, 5W-30 and 10W-30, and indicates 5W-30 for ALL temperatures, and 10W-30 only for temperatures above freezing. That makes sense to me.

There is some overlap in the temperature range of the oils in the Cadillac. I would NOT use 5W-30 oil in a pre-2000 Northstar. What works for Chrysler may not work for the Northstar and vice versa. The dealer that Jim mentioned is just another example of a dealership not following the manufacturer's recommended practice. When a customer has a problem with their engine due to the dealer using the incorrect grade of oil, you can be sure the dealer will blame the engine, Cadillac, GM, etc. - everything but their failure to use the proper grade of oil.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Hi,

but why does my original Cadillac owner's manual calls for 5W30 all year round then (see attachment above)

This manual was supplied with the new car in 1996.

In the engine compartment there is a sticker which says (translated) "check owner's manual for correct oil grade" right beside the filler cap which has the 10W30 script? I'm puzzled...perhaps it's really not that important.

Stefan

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^ that is intresting. The graphic for your car is differant than the one provided in mine. Could someone with a 96 US seville post thiers, couldbe the company that made the over seas manual made a mistake? Who knows.

The Green's Machines

1998 Deville - high mileage, keeps on going, custom cat-back exhaust

2003 Seville - stock low mileage goodness!

2004 Grand Prix GTP CompG - Smaller supercharger pulley, Ported Exhaust Manifolds, Dyno tune, etc

1998 Firebird Formula - 408 LQ9 Stroker motor swap and all sorts of go fast stuff

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The FSM for 1997 on page 0B-4 has a graphic on recommended grades of engine oils. The subheading text is

For best fuel economy and cold starting, select the lowest SAE viscosity grade oil for the expected temperature range.
The graphic with the thermometer and arrows shows
  • Arrow from +60F downward: SAE 5W-30
  • Arrow from 0 F upward: SAE 10W-30 preferred above 0 F
Other text:
If neither SAE 5W-30 nor SAE 10W-30 grade oils are available, SAE 30 grade may be used at temperatures above 40 degrees F (4 degrees C)
Do not use SAE 20W-50 or any other grade oil [that is] not recommended.

The text that addresses this figure is on pages 0B-3 and 0B-4. It begins by recommending 10W-30 when the temperature is above 0 F. There is a typo on the Centigrade number; it says 18 C and should say -18 C. It says that

When the temperature will be very cold and never above 60 F (16 C), SAE 5W-30 should be used in all models. SAE 20W-40 or oils of other viscosity rating or quality designations are NOT recommended at anytime.
We should be careful about oversimplified interpretation of the thermometer graphic. Except for cold starting, the engine oil temperature is determined by the cooling system and the engine, not the outside temperature. Thus either grade oil is fine for a warm engine (and nnW-40 or nnW-50 oils are specifically NOT recommended), which is reasonable and perfectly logical. For cold starting, the 10W-30 oil is recommended only for temperatures above 0 F. If the car can be started hot with 10W-30, it can be started cold in weather above 60 F with 5W-30 oil in it. Thus 5W-30 oil is fine for any temperature.

There is no mention of synthetic oil at all in the FSM for 1997 E/K bodies. If you are insecure about starting a hot engine when it has been run in hot weather with 5W-30 in it, use synthetic 5W-30. The dealers do NOT use 5W-30 refined oil in Northstars in the summertime to my knowledge; anyone know more?

What all of this thread seems to be saying to me is that either 5W-30 or 10W-30 is fine if you don't do cold starts for an engine that is below 0 F with 10W-30, and the oil is rated for use in modern automobile engines. We have several owners who have chimed in with good long-term experience with both grades – refined, synthetic, blends, and high-mileage. So, I would venture that the choice is the owner's preference.

I will add to this already over-long post by saying that I would never use 30W oil in my Cadillac except as an emergency to get to a filling station where I would drain it and put in 5W-30 Mobil 1. A quart of 10W-30 to get to the next oil change a month or two away would not bother me, even if it was refined oil.

In my previous car, a 1990 Grand Am Quad 4 HO, the dealer's free oil change was 30W in the summer. The engine was very noticeably sluggish, and the oil began to break down after about a week. I drained it and replaced it with 5W-30 synthetic, as recommended for that car (synthetic was mentioned for hard usage, I believe).

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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It may be that 10W-30 oils are not readily available in Europe? Many Fords and Chryslers and Hondas here specifiy 5W-20 oil, but I understand the exact same vehicle sold in other parts of the world specify 5W-30 oil.

I will stick with 10W-30 oil.

But having said that, the chart that Stefan posted makes more sense to me than the American version. 5W-30 oil can be used at any temperature range. 10W-30 oil can be used at MOST temperature ranges, except for the very coldest. What's odd about the American chart, at least in 1997, is the 5W-30 "range" stops at 60*F. It doesn't go any higher. In theory, a 5W-30 oil should be as good during warm temperatures as any 10W-30 oil.

But anyway...I will stick with 10W-30 oil...probably Havoline in the $9 jug at Wal-Mart.

Jason(2001 STS, White Diamond)

"When you turn your car on...does it return the favor?"

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^shearing, thats why I think it stops at 60.

The Green's Machines

1998 Deville - high mileage, keeps on going, custom cat-back exhaust

2003 Seville - stock low mileage goodness!

2004 Grand Prix GTP CompG - Smaller supercharger pulley, Ported Exhaust Manifolds, Dyno tune, etc

1998 Firebird Formula - 408 LQ9 Stroker motor swap and all sorts of go fast stuff

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^shearing, thats why I think it stops at 60.

But why not in the export version? Why not in other American owner's manuals, like my Chrysler? This Cadillac manual is the only one that shows the 5W-30 specifically stopping at 60*F.

I'm agreeing with Jim that it may not need to be taken literally, but I ask to myself, why the difference between this manual and most others I've seen? The export version that Stefan posted makes much more sense to me.

Jason(2001 STS, White Diamond)

"When you turn your car on...does it return the favor?"

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