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1999 Seville STS oil question


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Hi!

What viscosity would you prefer for a 1999 Seville STS? The manual and the filler cap suggests 10w30. But in Europe a 10w30 is almost impossible to get.

Is a 5w30 or a 10w40 the better choice? Both are Api SL. Temperature is never less than 0 F and in the summer 80-90 F.

I would think the 10w40 should be better at "hard" driving conditions such as high speeds where the oil temperature is pretty high.

Thank you!

Chris

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Hi!

What viscosity would you prefer for a 1999 Seville STS? The manual and the filler cap suggests 10w30. But in Europe a 10w30 is almost impossible to get.

Is a 5w30 or a 10w40 the better choice? Both are Api SL. Temperature is never less than 0 F and in the summer 80-90 F.

I would think the 10w40 should be better at "hard" driving conditions such as high speeds where the oil temperature is pretty high.

Thank you!

Chris

Personally, I wouldnt use either, it was spec'd for 10W30. My gut is that 5W30 would be fine in the winter months and 10W40 would be ok in the summer months, but that is just a gut feeling

Check with one of our board in Europe like the Cadillac Club Sweden and see what they are doing and what they have success with

http://caddyinfo.ipbhost.com/index.php?showforum=47

I am sure they will be able to help you or direct you toward a solution

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I'll ask them as well, thank you!

The local cadillac dealer uses 0w40 but I told him that I don't want it.

Another auto part show told me, that if 10w30 is suggested I can use a 10w40 as well, because it is only "better". Because I cannot run the engine without oil I currently use 10w40, but I'd like to know if I should get rid of it or if I can use it

I've searched the internet for the best oil for the Northstar, but couldn't find a perfect sollution. Does anyone know an online shop that would deliver 10w30 oil to me in Austria? Amsoil 10w30 or Mobil1 10w30 should be fine.

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The engine sounds quiet good (no knock-noises) with the 10w40.. my oil is called "super easy running" if i translate it... doesn't look much thicker than the 5w30 i use in my other car!

I read an article somewhere on the web that the Amsoil 10w30 is such a good oil, the only one that was better than the mobil1 10w30... if i could get it, I would try it, but most shops here told me that they never heared about a 10w30 and the other told me that it is not available and I should use the 10w40

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......I read an article somewhere on the web that the Amsoil 10w30 is such a good oil, the only one that was better than the mobil1 10w30....

You can find unedited - unverified - undocumented articles praising/endorsing anything from peanut butter to toilet tissue.

Motor oil is motor oil. If the oil brand claims API specification, that is all you need to know (in the case of USA built vehicles). Simply comply with the recommended viscosity if possible.

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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My suggestion would depend on exactly how you plan to drive the car. If your going to putt around town, or go on short easy trips, I'd favor the 5W-30. Mostly for the fuel economy potential, which can be a substantial money saver at the price of gasoline over there.

If you care very little about fuel economy, and plan to hold it at 100+ MPH on the Autobahn during the summer, go for the 10W-40.

My suggestion would also depend on the exact brand and specification of the oil itself. Is either one synthetic? I know that German made Castrol Syntec 0W-30 is thicker than most 10W-30's, and holds grade much better than most other oils. To learn more than you want to know about motor oil, go to bobistheoilguy.com and start reading. Those guys drink motor oil for breakfast.....and sell Amsoil (which I don't care for).

The single finest widely available (read WalMart) synthetic oil currently available in the US is Mobil1 Extended Protection (in various weights).

If you want Amsoil, check with this guy: http://lube-direct.com/gallan/

And finally, remember, the oil will only "act" like a 40 weight when it's at 100°C, not a cold 40 wt. but a hot 40wt. When it's colder than that, the chemistry will make its apparent viscosity thinner, down to the cold SAE 10 for winter starting. (which can be pretty thick when its cold)

Never underestimate the amount of a persons greed.

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I've been running 5W-30 Mobil 1 in my car for years. The differences between Amsoil and Mobil 1 are slight, both are just about the best you can get. However, in the final analysis, if your dealer recommends 10W-40, that's OK. My owner's manual says not to use oil in my 1997 model year Northstar that has the top number over 30.

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My manual tells me not to use 20w50 and that the best oil would be the 10w30

The liqui moly 10w40 I use is a synthetic oil, just like the mobil1 and amsoil 10w30

The temerature range here goes from about 14 to 90 degree fahrenheit and most times I driver longer distances and not very fast (average 85-90 on the highway).

So I think I can either use my 10w40 or order the 10w30 in the US. I'd like to compare fuel economy, oil temperature and oil consumption and use the "better" one.

I found a shop which delivers Mobil1 to Austria, the Amsoil Online Shop isn't available for customers from Europe :(

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I was surprised to see...my 2005 Mustang GT uses 5w-20 (?!). It does have a variable camshaft setup.

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There isn't much difference between 5W-30 and 10W-30. The 5W-30 flows a little better in a cold engine. My owners' manual recommends 5W-30 when the engine is started at temperatures of 0 F (-18 C) or lower. It doesn't say not to use 5W-30 in hot weather, and my Cadillac dealer recommended 5W-30 from about 2000 onwards.

From analysis that I have seen online, there is very little difference between Mobil 1 and Amsoil. They are both excellent oils and are probably unsurpassed among certified motor oils available on the market. Mobil 1 is less expensive and easier to get.

I would say that the "best" oil for your car for overall conditions would be 5W-30 Mobil 1 or Amsoil with 10W-30 Mobil 1 or Amsoil a very close second. I wouldn't hesitate to run 10W-40 in my car if that was all that was reasonably available but I would stay off the Authbahn, or at least stay at 90 mph (150 kph) or less for any extended period of time, because the thicker oil won't flow as well when hot. In nearly all engines, the pistons are lubricated and cooled by oil squirted up through restricted nozzles in the rod journals, and that flow won't increase with hotter oil the way it will with 10W-30 or 5W-30.

You will get the best fuel economy with 5W-30 Mobil 1 or Amsoil, and very nearly as good with 10W-30 Mobil 1 or Amsoil. Dino oil will not get you quite the fuel economy of synthetic.

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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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The problem I find with all of these discussions is the reduced ZDDP that to me is damaging to Northstars older than 2000 that have rubbing element lifters

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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bearing clearances are designed for 5w-30 or 10w-30. its the viscosity when hot that is important since 99% of your running is done warm/hot. 0w-30 is fine also. using 40w raises your oil pressure and restricts flow. you change the viscosity but do not/cannot change bearing clearance or restriction to flow.

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It is very easy to get 5w30 in Austria because it is very common, so if I can choose between 5w30 and 10w40 I should use the 5w30 because it is thinner when driving with "hot" engine?

Most times I set the cruise control to 90mph until I leave the "Autobahn" :)

When I bought the car a 5w30 was used and the oil consumption and noise of the engine weren't as good as with my 10w40 I use now. I could hear the hydraulic valve lifters a little bit with the 5w30, with the 10w40 it doesn't make much noise. Thats why I would like to use a 10W... oil.

(4 of the valve lifters were changed when the head gasket was replaced, the mechanican told me these 4 ones don't look too good and a change is recommend.)

I also found a shop that may send the Mobil1 10w30 EP to Austria, anyone knows a cheaper one? http://www.autobarn.net/mobil-oil.html

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XX-40 will give you more pressure which will quiet down a worn motor. how many miles were on the motor when the heads were pulled? why did your mechanic choose to pull the cams and check the lifters? worn lifters means worn cam lobes. changing lifters usually requires changing cams so the wear surfaces are in sync. many folks with worn lifters on pushrod motors will also change the camshaft. now you say the lifters were noisy. was this at idle or at speed on the highway?

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At idle you could hear the lifters a litte bit with the 5w30, wíth the 10w40 I can hear nothing. When driving at highway speeds or around town there is nothing "strange" to hear with both, the 5w and the 10w.

I don't know why he did that, he only told me a story of another Seville he had to repair some weeks ago because of bad lifters which was followed by a expensive repair. Maybe because of this he checked if everything looks alright. The engine now has 95.000 miles and about 90.000 miles when the head gaskets were changed.

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The problem I find with all of these discussions is the reduced ZDDP that to me is damaging to Northstars older than 2000 that have rubbing element lifters

I wouldn't worry about that too much, I doubt seriously that the GF4 spec (or is it SM spec?) is not fully backward compatible. We all know it was done in the intrest of increased catalytic converter life, now that cars are lasting well over 100,000 miles.

You will find that ample Moly and Boron, and maybe a few other extreme pressure additives is used to make up for the reduction of zinc, not to mention just a much more robust base stock. These new base stock synthetics are what make 0W-20 oils even possible. I'm sure you can remember when such an oil weight rating was unthinkable!

If you really are worried about it, a little GMOS or Valvoline Synpower Oil Treatment will help.

Never underestimate the amount of a persons greed.

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  • 4 weeks later...

Soon I will need an oil change.

I think I'll stick with my 10w40, except someone would like to send me a package with Mobil1 10W30 to Austria :) Online I would have to pay more for the shipping than for the oil itself...

I also will change the oil pan gasket, is it a good idea to try it by myself? Shouldn't be to complicated or am I wrong?

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Oh, that's not good :( The leak is not very big, so I won't change the oil pan gasket, thought it would be easier!

In the last months the oil consumption is about 0,5 to 0,7 quart every 1000 miles. When I drive faster than 95mph the oil consumption is bigger, but there is also much more "fresh" oil on the oil pan housing. If the change would have been easier, I had liked to see, how much oil consumption is caused by the gaskets (to see how much oil the engine burns... the exhaust gases don't show a problem, no blue smoke and no bad values when my dealer did test the exhaust gases)

Edited by -Chris-
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Oh, that's not good :( The leak is not very big, so I won't change the oil pan gasket, thought it would be easier!

In the last months the oil consumption is about 0,5 to 0,7 quart every 1000 miles. When I drive faster than 95mph the oil consumption is bigger, but there is also much more "fresh" oil on the oil pan housing. If the change would have been easier, I had liked to see, how much oil consumption is caused by the gaskets (to see how much oil the engine burns... the exhaust gases don't show a problem, no blue smoke and no bad values when my dealer did test the exhaust gases)

You might consider tightening all of the oil pan bolts that you can get to... if you have not already did that.

It may help "SOME".

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I was surprised to see...my 2005 Mustang GT uses 5w-20 (?!). It does have a variable camshaft setup.

Newer Ford Engines are designed for 5W-20 grade "Partial" Synthetic made by Ford [Motorcraft].

My 2006 5.4 L 300 HP Expedition requires it but the manual also says 5W-30 is Acceptable. I run 5W-30 full synthetic in it in the summer and sometimes 5W-20 in the Winter.

My 2003 Deville gets 5W-30 Synthetic as a margin of safety, probably overkill since it is changed every 4-5K miles at 50% oil life.

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