How often Do You Change Oil

[Cadillac Jim]

A crankshaft scraper is a piece of sheet metal bolted to the crankcase at the oil pan bolts on the side where the crankshaft rotation carries the rods from the crankcase up into the bores on the compression stroke. It is shaped to just clear the crankshaft and rods and to "scrape" the oil off so that the crankshaft does not carry large quantities of oil as rotating mass, as most engines do, particularly at high RPM. The phenomenon was discovered in the 1970's by GM engineers watching with windows into various parts of the engine and using high-speed stroboscopic photography. Crankshaft scrapers are used in racing engines.

Since all of the simple things to get high specific output are done in the base Northstar design since it first appeared in 1992 in the 1993 Allante -- four valves per cylinder, aluminum cylinder head with high compression, high lift long duration camshafts, high stability knock sensor controlled spark timing, individual port fuel injection and exhaust system with controlled resonances to generate and control torque and horsepower peaks, closed-loop mixture control built into the DFI, electronic transmission control integrated with the engine control and adaptive to driver history, etc., I would expect a crankshaft scraper to be in the design. But, I don't see one in the manual and I've never heard of one mentioned on caddyinfo.

[apache13]

I hear you guys but my driving is factored in as well....I hit around 2k to 2.5k miles every 3 months (2/3 of those miles include bumper-to-bumper Denver traffic at 8AM and 5PM). I dunno, I could extend or double the time period in between oil changes....of which I've heard nothing but bad things about the oil life monitor (people following the oil monitors in GM vehicles going 6-9 months in between oil changes because the monitor says the oil is still good). I like 3 month intervals...I was always taught that any longer than that regardless of mileage the oil will begin to break down........I'm not wasteing natural resources either LOL all of the discarded oil that we have from oil changes is recycled (I think recycled into new oil or something).

-Tony

[JimD]

I hear you guys but my driving is factored in as well....I hit around 2k to 2.5k miles every 3 months (2/3 of those miles include bumper-to-bumper Denver traffic at 8AM and 5PM).

The OLM factors in the type of driving your engine experiences.

I dunno, I could extend or double the time period in between oil changes....of which I've heard nothing but bad things about the oil life monitor (people following the oil monitors in GM vehicles going 6-9 months in between oil changes because the monitor says the oil is still good).

What you have heard about the OLM is not correct. My '04 DTS has a maximum mileage of ~~12,500 programmed into the OLM and that could easily be 12 months of "normal" driving. Not a problem for me.

I like 3 month intervals...I was always taught that any longer than that regardless of mileage the oil will begin to break down.

That might have been true in the past. But modern oils contain a chemical additive package that was unheard of in the '70s or '80s.

I doubt we will change your mind and that's OK with me. But the scientific evidence is there for you to ignore at your own risk.

[BodybyFisher]

I hear you guys but my driving is factored in as well....I hit around 2k to 2.5k miles every 3 months (2/3 of those miles include bumper-to-bumper Denver traffic at 8AM and 5PM). I dunno, I could extend or double the time period in between oil changes....of which I've heard nothing but bad things about the oil life monitor (people following the oil monitors in GM vehicles going 6-9 months in between oil changes because the monitor says the oil is still good). I like 3 month intervals...I was always taught that any longer than that regardless of mileage the oil will begin to break down........I'm not wasteing natural resources either LOL all of the discarded oil that we have from oil changes is recycled (I think recycled into new oil or something).

-Tony

Who said bad things? Have you done any research here regarding the Oil Life Monitor?.. ANYONE saying the OLM does not work or says bad things about is is 1) unknowledgable about it, 2) thick headed, 3) bias, 4) old school belt and suspenders to a FAULT, or 5) an AHOLE.

Have you read up on it yet? Yes or No? If No, I can post you a lot of bedtime reading that will set you straight. Pay no attention to AHOLES most are clueless or unknowing or unknowledgable.

Your SN is apache, are you of apache descent? If so, you of all people should understand conserving and the environment

[apache13]

Your SN is apache, are you of apache descent? If so, you of all people should understand conserving and the environment

Um no dude...that's the name assigned to me for e-mail at Metro State....not cool dude

[Ranger]

I like 3 month intervals...I was always taught that any longer than that regardless of mileage the oil will begin to break down

That is old school thinking. Times. engines and oils have changed greatly.

[BodybyFisher]

Your SN is apache, are you of apache descent? If so, you of all people should understand conserving and the environment

Um no dude...that's the name assigned to me for e-mail at Metro State....not cool dude

Not cool why? Is there something wrong with asking if you are of Apache descent? Typically members use names that have significance to them, members normally do not use assigned names, and names are NOT assigned at caddyinfo. Fill me in I am lost

[Jan Olsson]

I change when the OLM tells me to. There is still a safety factor of 2 according to the guru....

Regular WOT treatment keeps oil consumption at very low levels. I drove about 10000 miles until my first oil change since I bought it . When I bought it (in July) it had about 75% left so that would make that oil change roughly a 12500 mile interval.

During that time I only had to top of with a quarter of oil.

I use what they recommend. 5W-30 oil for all seasons.

For those of you with a Northstar made before 2000 the guru recommends either to spike the oil with EOS or to use an oil for diesel engines (like a 15W/40 diesel oil since it can be hard to get a 10W/30 oil for diesel engines) since they must have a higher degree of ZDDP than a gasoline engine. The 15W/40 won´t hurt anything just decrease your mileage. DON´T use a new oil with the starburst symbol. I believe that the ZDDP is as low as 1/10 of what oils were like in -93. It might be just fine but remember that the ZDDP lubricates sliding surfaces with great pressure where the oil itself is not sufficient, 32 flat tappets for instance...

The redesign with roller followers in -00 was one way to reduce the amount of ZDDP needed in the engine oil.

I used Texaco Eurotex 10W/30. An oil with API grade SG.

Someone here changed at 50% when using a newer oil (like SL/SM). But he should change at 90% just to be sure...or use a diesel oil and change a 0%.

My advise would be to use what´s recommended in a -00 and newer.

In a older than -00 use what´s recommended but if you can´t find it use a diesel oil instead and NOT a new formula oil!

[clarkz71]

You can order the 10/30 Rotella diesel oil at any one of the auto parts, O'Rielly's

for instance.

[JasonA]

I buy mine (Shell Rotella 10W-30) at Wal-Mart.

[bowtie123]

Has anyone noticed...................

You can get a 5 quart jug of Mobil 1 at Walmart for $19.99

If you go to Advanced Auto or AutoZone they have what looks like

the same jug for about $23.00.......but it is only 4 quarts.

Can't beat WalMart!

[kcd1184]

I change when the OLM tells me to. There is still a safety factor of 2 according to the guru....

Regular WOT treatment keeps oil consumption at very low levels. I drove about 10000 miles until my first oil change since I bought it . When I bought it (in July) it had about 75% left so that would make that oil change roughly a 12500 mile interval.

During that time I only had to top of with a quarter of oil.

I use what they recommend. 5W-30 oil for all seasons.

For those of you with a Northstar made before 2000 the guru recommends either to spike the oil with EOS or to use an oil for diesel engines (like a 15W/40 diesel oil since it can be hard to get a 10W/30 oil for diesel engines) since they must have a higher degree of ZDDP than a gasoline engine. The 15W/40 won´t hurt anything just decrease your mileage. DON´T use a new oil with the starburst symbol. I believe that the ZDDP is as low as 1/10 of what oils were like in -93. It might be just fine but remember that the ZDDP lubricates sliding surfaces with great pressure where the oil itself is not sufficient, 32 flat tappets for instance...

The redesign with roller followers in -00 was one way to reduce the amount of ZDDP needed in the engine oil.

I used Texaco Eurotex 10W/30. An oil with API grade SG.

Someone here changed at 50% when using a newer oil (like SL/SM). But he should change at 90% just to be sure...or use a diesel oil and change a 0%.

My advise would be to use what´s recommended in a -00 and newer.

In a older than -00 use what´s recommended but if you can´t find it use a diesel oil instead and NOT a new formula oil!

I don't remember the OES or diesel oil statements on pre 2000 N*s from the Guru. I must have missed it. If He did say that, I am very interested.

Kent

[Jan Olsson]

QUOTE (Jan Olsson @ Oct 25 2007, 01:14 PM)

I change when the OLM tells me to. There is still a safety factor of 2 according to the guru....

Regular WOT treatment keeps oil consumption at very low levels. I drove about 10000 miles until my first oil change since I bought it . When I bought it (in July) it had about 75% left so that would make that oil change roughly a 12500 mile interval.

During that time I only had to top of with a quarter of oil.

I use what they recommend. 5W-30 oil for all seasons.

For those of you with a Northstar made before 2000 the guru recommends either to spike the oil with EOS or to use an oil for diesel engines (like a 15W/40 diesel oil since it can be hard to get a 10W/30 oil for diesel engines) since they must have a higher degree of ZDDP than a gasoline engine. The 15W/40 won´t hurt anything just decrease your mileage. DON´T use a new oil with the starburst symbol. I believe that the ZDDP is as low as 1/10 of what oils were like in -93. It might be just fine but remember that the ZDDP lubricates sliding surfaces with great pressure where the oil itself is not sufficient, 32 flat tappets for instance...

The redesign with roller followers in -00 was one way to reduce the amount of ZDDP needed in the engine oil.

I used Texaco Eurotex 10W/30. An oil with API grade SG.

Someone here changed at 50% when using a newer oil (like SL/SM). But he should change at 90% just to be sure...or use a diesel oil and change a 0%.

My advise would be to use what´s recommended in a -00 and newer.

In a older than -00 use what´s recommended but if you can´t find it use a diesel oil instead and NOT a new formula oil!

I don't remember the OES or diesel oil statements on pre 2000 N*s from the Guru. I must have missed it. If He did say that, I am very interested.

I asked him on the other forum once.

Look here.

Your english is fine. Better than my German or whatever.....LOL

You are correct in assuming that the later API grades such as SL or SM are "better" and , as such, supercede the earlier grades. That is conventional wisdom and is pretty much the case as one of the API requirements is that "improved" performance grades supercede prior grades and are always backwards compatible.

Having said that.....the current crop of oils "rated for gasoline engines" that are on the shelf in the most obvious locations in the stores are also "fuel economy" oils. Any oil with the ILSAC "starburst" symbol that says "for gasoline engines" is a bit of a hybrid....those oils meet the latest API performance specs, have the minimum allowable ZDP (to prevent catalyst contamination) and have friction modifiers in the oil for fuel economy improvement.

The difference is that the API specs just relate to the oil's performance as tested on gasoline engines. API specs have nothing to do with friction modifiers or MINIMUM ZDP levels. The API specs just have minimum performance specifications based on actual engine testing.

Understand that the API performance specs have a lot of requirements besides just "wear protection". Most all of the improvement in the latest grades is in the area of temperature protection. The latest oils will still perform at hotter and hotter engine temperatures. So they are "better" in that the older oils might start to oxidize and give up around 290 degrees F and the latest oils will still function well at 310 or 315 degrees F. They are not "better" in that they give more wear protection.....they just have better high temperature resistence, among other things.

More modern, current production engines are designed to run with the minimum ZDP oils and friction modified oils. Clearances are changed, designs are changed to add roller followers everywhere that are not ZDP dependent for preventing wear, wear surfaces are hardened where necessary, etc.....

Older engines designed for the SF and SG oils that had more ZDP in them are not as well protected against ZDP depleted oils.

So...technically the older engines should be OK with the new SM oils since the SM oils "technically" supercede the older oils and are backwards compatible. But the newer oils probably are " barely" adequate in terms of anti-wear additives such as ZDP. If the engine is perfect inside it will likely be fine. But if the engine is marginal for wear the ZDP depleted oil MIGHT cause a problem and accelerate wear. Certainly you would not want to use the newer ZDP reduced oils for long change intervals in the older engines.

An older 93 Northstar, for instance, has 32 rubbing element tappets (flat tappets) that require much more ZDP for protection against wear than the 2000 and later Northstars with roller tappets.

If you want to be sure your engine has the best wear protection you can do two things. One, use one of the non-"gasoline engine" oils such as the diesel Rotella or Delvac or Delo oils. Those oils have much more anti-wear protection since they are also certified for diesel use. The other thing you can do is to spike the oil you are using with extra ZDP by adding a pint or quart of GM EOS (General Motors Engine Oil Supplement). The EOS is available at any GM parts counter and is sold as an assembly lube. It is basically plain motor oil with a high concentration of ZDP that will fortify any crankcase fill with the extra ZDP desired for more anti-wear protection. It is the only oil "additive" I would ever recommend as it is specifically designed for this purpose.

If you look at the container of Rotella/Delvac/Delo oil you will see in the fine print that it meets all the API diesel performance specs (combinations of the letters CC and CD, etc.) AND it meets the latest gasoline API performance specs such as SL or SM. Now look at the ILSAC "for gasoline engine" oil across the isle in the autoparts store. Read the fine print. It meets the API gasoline SM specs but does NOT meet any of the diesel performance specs. The diesel specific oil is a much "better" product in terms of wear protection if your engine needs it. Diesels have a much greater need for anti-wear protection due to the soot and combustion byproduct contamination of the oil due to the high compression and high cylinder pressures of the diesel engine, so the oils for diesels have to be much better.

I would recommend the Rotella/Delvac/Delo oils for the 93-99 Northstars, personally. The latest ILSAC fuel economy oils are getting very low in ZDP concentration. Fine with the newest engines on the road but not so fine for a 93 Northstar.

You can get the Rotella/Delvac/Delo oils in 10W30 for your engine but they are much harder to find. Check a truck stop or large equipment supplier. If all you can find is the 15W40 version of the Rotella/Delvac/Delo that is fine in the 93 Northstar. The oil is not that much thicker to hurt anything unless you live in the far north and need to cold start at -40.

The other option is to use one of the "severe service" oils marketed by Mobil that are designed for longer change intervals and marketed as such. If you read those bottles you will notice that they also do NOT meet the ILSAC "for gasoline engine" use as they do not have the ILSAC starburst symbol. That is because those oils designed specifically for longer change intervals also have more ZDP in them that excedes the amount allowed for the ILSAC starburst designation.

I would recommend the conventional diesel Rotella/Delvac/Delo oils. I personally use the Delvac (Mobil) in most everything around the house.

Hope I didn't make this more confusing.

[BodybyFisher]

Thanks Jan, that's good info

[MAC]

So after all is said and done, when I was advised not to use diesel oil (Rotella, Delvac, etc.) because of potential engine damage caused by high detergent and other additives, such advice is not accurate? I think this is an important topic because we don't want to use the wrong oil. The Guru said that diesel oil can be used in older Northstars--which is all I need to know as I trust his wisdom. But has anything changed to diesel oils since his statement, such as formulations, which may cause problems for our Northstars?

[JasonA]

I don't think any "diesel oil" is going to damage your engine. I said earlier -- certain factions (like that ZDDP additive company) have a lot to gain by scaring you off "diesel oil" and into a regular passenger car oil, only to supplement it with their product.

Remember also..."diesel oil" is oil that is rated Cx (vs. Sx, like SL, SM, etc). If you look on most any oil out there, even passenger car oils, many of them are also rated CF. The Pennzoil Platinum I just dumped into my STS is rated SM (for gasoline engines) and CF (for diesel engines). Have a look at the website and click on the link for the Product Data Sheets:

http://www.pennzoil.com/products/motor_oil/platinum.html

Most oils you see on the shelf are dual-rated (such as CF/SM). A LOT of people run the traditional "diesel" oils in their cars (like Shell Rotella, Mobil Delvac, and Chevron Delo) with great success -- because they are such stout oils. As long as the oil is rated for gasoline engines (SM is the latest gasoline engine specification), it'll be fine in your car.

[beg]

I change at 10K miles MLO at 10-20%, I drive about 45K miles/year and it works good. I use a Swedish syntetic oil but it's a waste it's ok to drive with a ordinary oil like i used to do in my -97 STS.

I have a Pontiac Bonneville SSE -91 gone 261Kmiles used mineraloil 10W/30 and it works great.

I have also bought a Chevy K2500 -00 gone 530K miles (before it has worked as a newspaper distribuator) works great and goes also with 10W/30 mineral oil.

Yesterday I sold my STS and will by a newer STS or CTS and I will continue to follow the service intervalls and/or the MLO