1988 BMW M6 oil choice

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I have a 1988 BMW M6 with the stock S38 engine. The vehicle has under 70K miles. This engine is a 6 cylinder with 24 overhead valves and 6 individual throttles. It was their top of the line in those years. I do not know what the previous owner used for oil.

I am considering a 20-50 or 15-50 for a motor oil. The vehicle is exclusively used in southern warm climates. The winter temperature never gets below 50F. Summer time can be as warm as 85F.

The vehicle will not be driven much so preservation is important. However, once running, it will get some spirited driving to the 7000 RPM redline (after warm up, of course!)

I am considering Red Line for all the oil needs (including gear box and rear diff). However, many BMW folks recommend Kendall GT1 in 20-50. I have heard all kinds of claims about dinosaur oils being superior in these older engines.

Cost is not an issue and the oil will be changed annually regardless of mileage (which should be low).

Any suggestions?
 
85°F max in Orlando? Huh? Anyway, RL is a good place to start. Any UOAs on the oil from this track(?) car? Any plans for modifications? How do the internals look? What is typcial oil pressure ranges? Do you know the previous fluid change intervals?
 
Nice car. I ran one from 1992-1995. I used Mobil 1 15W-50 year round with absolutely no problems. AFAIK the car is still running strong in the hands of its fourth owner.
 
The internals will be inspected along with a valve adjustment very soon. That is when I will perform the oil change. The previous owner did change the oil but was not specific about type/interval for his 10 years of ownership. I suspect it was always dinosaur oil and just a regular shelf brand. The bottom line here is synthetic or dinosaur oil. For synthetic, I would probably prefer RL or the new BMW Castrol 10-60.
 
Most M cars have an oil cooler (not sure about your specifically) which means that your oil temps are "controlled" in most circumstances. I, personally, would run a good 40 weight and not go as far as 50s or 60s unless there was a very good reason to do so. Depending on your climate and use, you wouldn't need a 0W so you could get something a little more shear stable. Search the UOA forum for results on your engine.

I'd also do a round of AutoRX at that age, mileage, and somewhat unknown past history. During ARX I'd probably use a 15W40 HDEO. Since you're in a Disneyland, you don't have winter so it's not a big concern.
 
I don't believe this car has an oil cooler. I checked on www.realoem.com and looked over the oil system. There is no listing for a cooler there. I have only had the vehicle for a few months and have not looked in that great detail.

Having said that, the issue of synthetic verses dinosaur oil takes on more importance. My primary mechanic, a member of the Technical Advisor staff for the BMW Car Club of America, told me that the engine design had very small openings that would not be properly lubricated by synthetics. I think that is hog wash but thats exactly why I am on this forum asking for help.

Will the synthetics do the job better than say Kendall GT in a 20-50W
 
I'm unable to browse parts on realoem for your car, they only show the new M6.
This place shows replacement oil coolers.

AutohausAZ shows replacement seals for the "oil cooler lines".

I've found part# 17 20 1 719 262 as an "oil cooler" for the M635CSi from 1988.

I'd take another look at your vehicle instead of web pages.

While groupIII oils are very good, you have a special interest vehicle there, and I would want to use a synthetic in it.

I also think that BMWCCA advisor's comment on small passages not being lubricated by synthetic is ----, but it would be nice to have more information on what he's referring to before making that decision. Today's dinos differ so much from 1988 dinos that if there was going to be an issue you'd probably have problems with groupIII too.

I'd probably throw some GTX 10W40 in there with AutoRX to get started. There have been some excellent 90s BMW UOAs with GTX 10W40 and I think it's trustworthy and shear stable.
 
Quote:

...However, many BMW folks recommend Kendall GT1 in 20-50. I have heard all kinds of claims about dinosaur oils being superior in these older engines....

Click to expand...


I don't think they make it anymore since Conco-Philips bought them out. I think they might make a 10W-50 semi-syn though...

If you want to use a conventional, I'd consider Valvoline VR-1 20W-50...

Pennzoil also makes a Group III syn 15W-50 (Platinum)...
 
http://www.amsoil.com/scripts/runisa.dll?amsoiloaf.1835332:RIGHTPANEL:1278865070:M6,BW,S,769

This is the correct link for the Amsoil web site. Thanks.


Regarding the owner's manual, the car did not come with one. That item is harder to find on Ebay than a Dodo bird. Apparently they are no longer made for that year.

I have submitted a request on the Big Coupe forum for that information and will get back with the factory recommendation.
 
rotella syn 5w-40 or shaffer's 5w-40 or delvac 1 5w-40/M1 5w-40 TDT.

After much analysis on the M42 E30 (apples to oranges but only to some extent, that engine is similar to some o the v12 type engines used in the 8-series and other cars), I found that a 15w-50 and 20w-50 don't do much for protection or wear prevention vs. a HDEO, and only lower fuel economy...

Ive been super happy with the brands above in mine, specced for the 15w-50/20w-50 grades.

JMH
 
Quote:

http://www.amsoil.com/scripts/runisa.dll?amsoiloaf.1835332:RIGHTPANEL:1278865070:M6,BW,S,769

This is the correct link for the Amsoil web site. Thanks.


Regarding the owner's manual, the car did not come with one. That item is harder to find on Ebay than a Dodo bird. Apparently they are no longer made for that year.

I have submitted a request on the Big Coupe forum for that information and will get back with the factory recommendation.

Click to expand...


Have you tried this place for your manual?
http://data.bmrparts.com/bmwparts/20162071645846U.html
 
Quote:

rotella syn 5w-40 or shaffer's 5w-40 or delvac 1 5w-40/M1 5w-40 TDT.

After much analysis on the M42 E30 (apples to oranges but only to some extent, that engine is similar to some o the v12 type engines used in the 8-series and other cars), I found that a 15w-50 and 20w-50 don't do much for protection or wear prevention vs. a HDEO, and only lower fuel economy...

Ive been super happy with the brands above in mine, specced for the 15w-50/20w-50 grades.

JMH

Click to expand...



I am unfamiliar with those brands. I need to do some more research. A different Tech Advisor for the Roundel Magazine seems to like Red Line oils. Are the ones you suggest similar?

What is an "HDEO" ?
 
Here's the secret decoder ring for the forum shorthand notations that you received:

"rotella syn 5w-40" is Shell Rotella 5w-40 heavy duty engine oil

"shaffer's 5w-40" is Schaeffer Manufacturing Co. "Supreme 9000 SAE 5W-40" http://www.schaefferoil.com/supreme_9000.html

"delvac 1 5w-40" is Mobil Delvac-1 5w-40 heavy duty engine oil

"M1 5w-40 TDT" is Mobil 1 Turbo Diesel Truck 5w-40.

You can get Shaeffer from a site sponsor, and the Mobil and Shell products from most oil retailers. Try Costco and Walmart.

An "HDEO" is "heavy duty engine oil" meant for large diesel engines. Their additive packages work well for older gasoline engines.

Red Line is a great oil, but for your use it probably won't be measurably better than the HDEO choices.


Quote:


I am unfamiliar with those brands. I need to do some more research. A different Tech Advisor for the Roundel Magazine seems to like Red Line oils. Are the ones you suggest similar?

What is an "HDEO" ?

Click to expand...
 
I'd go with something heavier, but it depends on how much you want to spend. You could get away with a HDEO just fine I'd imagine.
 
Kendall GT-1 Synthetic Blend 10w50...sure would like to see a UOA of this oil...We do have in our UOA forums an excellent Amsoil AMO 10w40 UOA of a BMW M3 that saw track work...If I had an 80's Bimmer this is what I'd run...

Please contact a site sponsor to buy Amsoil AMO.
 
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