Differential Oil Weight

[m3f_PhYrE_852fc25d8d]

First, thanks to PhYrE for the info on the gear oil.

Glad to be of service. It's a re-occuring topic with TONS of misinformation.


Second, has anyone found a Autozone/Napa type parts house that carries the Castrol SAF-XJ or Mobil products?

To my knowledge, the SAF-XJ isn't a distributed consumer-product, so you'll struggle to find it on shelves. Get a dealer to fill a jug for you. Alternately, Royal Purple 75W140 is a great gear oil. Their MaxGear line. Moderately priced and perfectly fine. Any good quality synthetic 75W140 with LSD additives will do the trick.[/QUOTE]


-M

[m3f_PhYrE_852fc25d8d]

the latest gear oil from bmw doesnt even specify the weight!



Because BMW has switched entirely to 75W140, as opposed to using 75W90 in regular diffs and 75W140 in LSDs.



-M

[m3f_pcarguy]

Glad to be of service. It's a Alternately, Royal Purple 75W140 is a great gear oil. Their MaxGear line. Moderately priced and perfectly fine. Any good quality synthetic 75W140 with LSD additives will do the trick.


I haven't found the Royal Purple in the 75w140 weight but as I said I found the Valvoline Synthetic in 90w140 w/ L.S. additives at the local O'Railey's (I know I butchered that spelling). I'll use that if I can't find something closer at one more place to check.


Again, thanks.

[m3f_Crosswire3]

I would just order the Royal Purple Maxline 75W140 from www.summitracing.com

[m3f_PhYrE_852fc25d8d]

I haven't found the Royal Purple in the 75w140


Any place that sells the products will bring it in upon request.


I would just order the Royal Purple Maxline 75W140 from www.summitracing.com


Yes, or online is right.

[m3f_tuyen]

i tried Redline 75w140NS. Bad mistake using the NS one, it contains no lsd additives. make my diff 'clunk' and 'grind' heaps. Shop didn't have any normal 75W140 though, so just bought castrol 80w140 lsd fluid. works a treat

[m3f_PhYrE_852fc25d8d]

i tried Redline 75w140NS. Bad mistake using the NS one, it contains no lsd additives. make my diff 'clunk' and 'grind' heaps. Shop didn't have any normal 75W140 though, so just bought castrol 80w140 lsd fluid. works a treat



Easier way would have been to buy a few-dollar bottle of LSD additive and poured it into the diff (really you should mix it before, but a good drive I'm sure will mix it up). Available in little 100-odd mL bottles from makers such as Redline, etc.



Yes, if you put oil that doesn't include modifiers for LSD clutches, you will get loads of chatter, as you experienced. You have an LSD. Use the proper oil. Why is this so challenging?



-M

[m3f_epj3_d2e882815a]

Sorry for bringing the thread back... but do people really put 75w90 in their dif's?!

[m3f_Oogie_M_9e4b5cf7b5]

Yes. Especially when its recommended by default off Turner and BavAuto websites.

[m3f_epj3_d2e882815a]

Yes. Especially when its recommended by default off Turner and BavAuto websites.


Bavauto, lol.


So factory recommendations don't mean anything?

[m3f_Oogie_M_9e4b5cf7b5]

Bavauto, lol.



So factory recommendations don't mean anything?



:clueless:



I didn't say I ran 75w90

[m3f_PhYrE_852fc25d8d]

Bavauto, lol.



So factory recommendations don't mean anything?



NO! This is not the FACTORY recommended for LSDs. It's recommended for the standard three-series differentials. M3 differentials take 75W140.



Besides- people can run whatever they want (just search for an engine oil thread). The question is still, as Ben best put it, you're asking whether you should run the right oil, a 75W140 oil that BMW recommends for your car, or something else. If you want to do something else... go nuts.



-M

[m3f_PhYrE_852fc25d8d]

Sorry for bringing the thread back... but do people really put 75w90 in their dif's?!



Search for the threads of the electric supercharger, snake oil additives, and more- people will buy and do pretty much anything. Double those chances if they read it on the Internet. Quadruple those chances if they see it on TV.



-M

[m3f_Richardspe_ff9fba485e]

Just another data point. The oil in the owners manual was for 75-90. BMW might have changed the spec in the TIS because they were going to use only 75-140. So instead of having the dealers stock both weights, they could just keep the 75-140 in the shop, and use it for everything.

[m3f_PhYrE_852fc25d8d]

Just another data point. The oil in the owners manual was for 75-90. BMW might have changed the spec in the TIS because they were going to use only 75-140. So instead of having the dealers stock both weights, they could just keep the 75-140 in the shop, and use it for everything.


There is no differential oil spec in the owners manual. The owners manual is so vague anyway. Are you saying that or have you checked it?

Under fluids, I have no mention of a differential or final drive. In the final drive section, there is no mention of fluids. In the specifications it says "approved HD gear oil".

Find me 75W90 in the M3 Owners manual that came with your car and win a cookie.


-M