Help with 91 BMW M5 - S38B36.

[shrike071]

Hi all -
I have a 91 M5 with the S38 engine. Anyone suggest a good oil? The engine is a detuned race engine from the factory... I was thinking about the good ol' GC, but wasn't sure. I live in Atlanta and the engine was rebuilt about 60k ago.

Your opinion is appreciated!

 

[d00df00d]

What was the factory oil? Was it the old BMW High Performance 15w-40? And I'm guessing BMW recommends an LL-01 oil now, correct?

 

[bmwtechguy]

I would probably not go much thinner than an HDEO 15W-40 for summer or 5W-40 in winter. If engine is still tight and no leaks or consumption, then a synthetic would be my choice. There are lots to choose from. For off the shelf, Rotella T6 5W-40 or other similar HDEO offer good performance for decent price. On the lower end of the viscosity spectrum, you could try GC or M1 0W-40. M1 T&SUV 5W-40 would be my oil of choice for M1. Other options are M1 10W-40 HM, or 15W-50 if you plan to run it hard in hot weather. Other retail oils you could use are Castrol Syntec 5W-40, 10W-40, or 5W-50.

Schaeffers 9000 5W-40 or 5W-50 (sold in gallons) are fine oils if you can find them, and Amsoil makes several oils which would work very well in that engine. We have site sponsors here for both of these brands. Finally, Redline makes a couple of oils that would be a great choice as well. These oils have limited local retail availability, but can be easily ordered online and are worth looking into.

 

[Audi Junkie]

SynPower 20w-50

 

[JHZR2]

Id run schaeffer's 5w-40 or rotella 5w-40 in there. It combines robustness with good cold startup characteristics.

Id also look at M1 HM 10w-40 or any standard HDEO 15w-40. Your owner's manual will provide a temperature versus viscosity chart that you should reference.

 

[shrike071]

I have been running M1 TDT in just about everything. Would it be a good fit here?

 

[Audi Junkie]

I'll second the M1 10w-40 HM.

 

[JHZR2]

Originally Posted By: shrike071
I have been running M1 TDT in just about everything. Would it be a good fit here?


Yes.

Also, in my 91 OM, BMW references standard grades in viscosity versus temperature, then shows a "special oils" column which is relevant across the entire temperature range. These special oils are likely the line-item for synthetics...

 

[d00df00d]

Originally Posted By: JHZR2
Also, in my 91 OM, BMW references standard grades in viscosity versus temperature, then shows a "special oils" column which is relevant across the entire temperature range. These special oils are likely the line-item for synthetics...

Not necessarily synthetics, just high-end stuff (at the time).

 

[bmwtechguy]

Originally Posted By: shrike071
I have been running M1 TDT in just about everything. Would it be a good fit here?


Yes, that would be a fine choice. I meant to say M1 TDT and not M1 T&SUV (where did that come from?) At least I typed the viscosity right...

 

[BMWTurboDzl]

I believe 15w40 can be cheaply bought at Global Imports.

 

[MCompact]

I ran 15W-50 M1 in my 1988 M6 and it worked fine.

 

[rainman49]

bmwtechguy, I've still got a few quarts of M1 T&SUV I bought on closeout at O'Reilly's. I use it in my Scag zero turn with Briggs 26hp ELS engine and my Kawasaki Prairie 650 ATV, both twin cylinders. Both run like champs with no consumption. I use GC in my wife's 530i with the same results. Of course, that's a completely different engine than the OP's.

 

[Connorb]

shrike071,
You're on bimmerforums, right? I recognize the user name, congrats on the car. I too recently bought a 93 M5 and live in a similar climate (Southern VA). The owner's manual recommends 15W-40 or 15W-50 for the S38.

After some debate between M1 10W-40HM/15W-50 and Red Line 15W-50, I decided to try the Red Line oil.