1988 BMW M6 oil choice
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The main problem with synthetic oil in the S38 is the timing chain tensioner, as it's hydraulic and uses engine oil. These are known to leak internally over time, and are known to cause timing chain rattles, especially on startup, with some synthetics oils.
Personally, if I were going to run a synthetic in that car - I'd run Castrol TWS 10W-16. The car spec'd a 20W-50 dino from the factory.
10W-16? not familiar with that one. 10W60?
Yes, sorry, I meant 10W-60
UOA
I think I'd lean more towards 40wt synthetics with this engine. Maybe a 50wt or 40-50wt blend in the summer.
Amsoil, Redline, RLI, Schaeffers, etc.
Rotella or M1 from Walmart if you don't feel like shopping around.
What does a gearbox of this vintage use? 90wt GL-4 or a thinner MTF?
Newer M lsd rears use 75W140 Castrol synthetic. SAF-XJ or SAF-XO, I don't remember which is thicker. Any 75W140 synthetic will work.
I think I'd lean more towards 40wt synthetics with this engine. Maybe a 50wt or 40-50wt blend in the summer.
Amsoil, Redline, RLI, Schaeffers, etc.
Rotella or M1 from Walmart if you don't feel like shopping around.
What does a gearbox of this vintage use? 90wt GL-4 or a thinner MTF?
Newer M lsd rears use 75W140 Castrol synthetic. SAF-XJ or SAF-XO, I don't remember which is thicker. Any 75W140 synthetic will work.
JHZR2
Staff member
SAF-XJ has become the standard for all rears serviced at the dealerships. So all BMWs worked on at the dealer have XJ fluid in them.
For transmisions of that vintage, fluid specs were all over the place, from GL-4 gear oil to ATF. Depended upon the sticker color or spec of the trans.
As for engine oil, I concur regarding using schaeffer's. With an HT/HS of 4.57, its a robust oil to take any sort of beating that the engine can provide.
JMH
http://www.ge39.com/files/SAF_XO_SAF_XJ_B1174_96.pdf
lsd rears get SAF-XJ 75W140
regular diffs get SAF-XO 75W90
http://www.opieoils.co.uk/performance_lubricants/pdf/castrol/CastrolSAFXJ.pdf
http://www.opieoils.co.uk/performance_lubricants/pdf/castrol/CastrolSAFXO.pdf
lsd rears get SAF-XJ 75W140
regular diffs get SAF-XO 75W90
http://www.opieoils.co.uk/performance_lubricants/pdf/castrol/CastrolSAFXJ.pdf
http://www.opieoils.co.uk/performance_lubricants/pdf/castrol/CastrolSAFXO.pdf
JHZR2
Staff member
The SAF-XJ fluid supercedes the SAF-XLS fluid, the TSB that I just reread does not mention the XO fluid...
That said, doesnt the M6 have an LSD standard? If so, an LSD-modified 75w-140 is still what BMW reccomends. XJ has replaced all other products for LSDs, so it is what it ought to get. Many folks in my E30 forum require 140 fluids even in non-lsd apps, because of diff whine.
JMH
That said, doesnt the M6 have an LSD standard? If so, an LSD-modified 75w-140 is still what BMW reccomends. XJ has replaced all other products for LSDs, so it is what it ought to get. Many folks in my E30 forum require 140 fluids even in non-lsd apps, because of diff whine.
JMH
I'd guess that it had an LSD but I'm not sure so I listed both options.
How many miles do these folks have on their E30's and could some of the diffs need new bearings or even R&P gears? Rear diffs are often neglected.
the 7th hit when you google "bmw differential wear" is www.e30eta.com/ecdiff.htm
How many miles do these folks have on their E30's and could some of the diffs need new bearings or even R&P gears? Rear diffs are often neglected.
the 7th hit when you google "bmw differential wear" is www.e30eta.com/ecdiff.htm
I put nothing but Redline 75W-90 hear oil in the rear diff, and Redline MTL in my older BMW's. The diff's call for 80W-90. And yes, the spec was all over the place for some of the trans. They work great with MTL, and I've seen MTL fix ALOT of hard-shifting condistions, as well as gear clash on alot of those older trannies as well. The M6 should have the G280 dogleg in it iirc, which MTL works great in.
I have yet to see any BMW diff that needs bearings, regardless of mileage. Regular practice is to yank one fro the yard, put new fluid in it, and drive it. Unless you're tracking it, rarely is anything more than seals and/or gaskets required for maintenance. I have yet to see a failed BMW diff that hasn't been tracked. The M6 has a large case 3.91.
FWIW - my current diff in my E30 came from a wrecked 318is, it's a small-case 4.10. I don't think it's ever been apart, I put Redline 75W-90 in it. Pinion seal started leaking due to a broken spring on the seal, I yanked that, replaced the seal, put it back together and back in the car, and have yet to have another issue. The car has now seen 2 full weekends at Road Atlanta, as well as a full season of autox, and very, very hard street driving.
I have yet to see any BMW diff that needs bearings, regardless of mileage. Regular practice is to yank one fro the yard, put new fluid in it, and drive it. Unless you're tracking it, rarely is anything more than seals and/or gaskets required for maintenance. I have yet to see a failed BMW diff that hasn't been tracked. The M6 has a large case 3.91.
FWIW - my current diff in my E30 came from a wrecked 318is, it's a small-case 4.10. I don't think it's ever been apart, I put Redline 75W-90 in it. Pinion seal started leaking due to a broken spring on the seal, I yanked that, replaced the seal, put it back together and back in the car, and have yet to have another issue. The car has now seen 2 full weekends at Road Atlanta, as well as a full season of autox, and very, very hard street driving.
JHZR2
Staff member
fail, maybe not... but E30 diffs whine like there s no tomorrow...
JMH
JMH
Originally Posted By: JHZR2
fail, maybe not... but E30 diffs whine like there s no tomorrow...
JMH
I have no idea what you're talking about, mine doesn't make a peep, neither has most of the ones I've worked on or driven, or owned. Transmissions, OTOH.......... Those whine like no tomorrow because they've been ran low on oil. Thankfully, they're fairly indestructible (unless you are REALLY abusing them).
fail, maybe not... but E30 diffs whine like there s no tomorrow...
JMH
I have no idea what you're talking about, mine doesn't make a peep, neither has most of the ones I've worked on or driven, or owned. Transmissions, OTOH.......... Those whine like no tomorrow because they've been ran low on oil. Thankfully, they're fairly indestructible (unless you are REALLY abusing them).
JHZR2
Staff member
fine, don't know it then. There are LOTS of complaints out there, especially in the small case units. Redline helps a bit for whatever reason. As my car was a flood vehicle (I knew it when i bought it, and it looks and runs like new), I can understand the first diff being bad. However, after getting a second from a VERY reputable BMW performance shop, and it being a flop, they ran and pre-tested two more before sending me the one in my car. And Im not the only one. Dont want to believe me, that's fine. Maybe Im just more picky or dont have my radio as loud or something...
JMH
JMH
Originally Posted By: KenO
Originally Posted By: JHZR2
fail, maybe not... but E30 diffs whine like there s no tomorrow...
JMH
I have no idea what you're talking about, mine doesn't make a peep, neither has most of the ones I've worked on or driven, or owned. Transmissions, OTOH.......... Those whine like no tomorrow because they've been ran low on oil. Thankfully, they're fairly indestructible (unless you are REALLY abusing them).
Second this. I have been screwing around with BMW's for 15+ years now and have put in several LS diffs from junkyards and never had a problem or whine. I also agree, the Getrag trannys work best with Redline MTL, and 75w-90 in the diffs.
Originally Posted By: JHZR2
fail, maybe not... but E30 diffs whine like there s no tomorrow...
JMH
I have no idea what you're talking about, mine doesn't make a peep, neither has most of the ones I've worked on or driven, or owned. Transmissions, OTOH.......... Those whine like no tomorrow because they've been ran low on oil. Thankfully, they're fairly indestructible (unless you are REALLY abusing them).
Second this. I have been screwing around with BMW's for 15+ years now and have put in several LS diffs from junkyards and never had a problem or whine. I also agree, the Getrag trannys work best with Redline MTL, and 75w-90 in the diffs.
Any updates? Has the original poster decided on an oil? I have an E30 M3 S14 which is basically the same engine minus 2 cylinders. I've been thinking of running 10w-40 redline or amsoil. Perhaps even a HDEO 15w-40.
If you look at BMW's oil for these older engines (available from dealership parts dept) it's a 15w40 HDEO. Rotella syn 5w40 seems like a good choice.
Maybe try using RL 5w40 over the 10w40 since the 5w is thicker when hot and the HTHS is about the same.
http://www.redlineoil.com/pdf/4.pdf
Maybe try using RL 5w40 over the 10w40 since the 5w is thicker when hot and the HTHS is about the same.
http://www.redlineoil.com/pdf/4.pdf
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