Redline 75w-90 in 1991 BMW 318i Differential

JHZR2

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This is redline 75w-90 from the 4.10 LSD in my 1991 BMW 318i. The 318i doesnt use a standard BMW diff, it is slightly smaller and has slightly less capacity. The cover is finned, but I believe the oil gets very hot. BMW recommends Castrol XJ fluid (IIRC) which is a 75w-140 in all LSDs based upon a TSB. I refilled with a Specialty Formulations diff fluid and definitely found that the diff quieted a bit (these diffs are also known to be a bit whiny).
 Code:

 Sample Date	1/13/2008
 Unit Age	111425m
 Comp Age	111425m
 Time on Oil	9925m
 Oil Maint.	Changed
 Fluid	Redline 75w90


 Fe	188
 Cr	2
 Ni	1.2
 Ti	0.6
 Ag	0
 Al	11
 Pb	0.1
 Cu	0.6
 Sn	1.6
 Si	166
 Na	2.4
 K	1.5
 B	146
 Ba	0.3
 Mo	7.5
 Mg	0
 Ca	70
 P	831
 Zn	31
 S	14997
 Cd	0
 Mn	3.7
 V	0
 Sb	0.2
 [email protected]°C142.6
 White Metal	NONE
 Babbitt	NONE
 Precipitate	NONE
 Silt	        NONE
 Debris	        NONE
 Dirt	        NONE
 Appearance	NORML
 Odor	        NORML
 H2O(Emul)	NEG
 H2O(Free)	NEG


 

JHZR2

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I felt like the 140 oil made a bit of a difference in terms of sluggishness.. The SF diff oil is more like a heavy 90wt (i.e. like a 75w-110, I believe), and works great. Id go that route before taking a full penalty of a 75w-140 in this car. THe M42 response is nice and perfect for commuting, since my current drive rarely gets all systems up to full temperature, I'd rather try to optimize operation without parasitic drags where possible.
 
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~200ppm in <10k miles isn't looking good. Definitely need thicker especially if it is required. A VOA of the Redline would've been interesting. Contamination? P doesn't look like a GL5. Ask for a retest from the lab.
 

MolaKule

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I also noticed you have a high silicon content. Now Redline does use a lot of anti-foam, but this seems high. Does this diffy have a breather hose? I would not expect 188ppm for this short of a mileage. I have seen 150-250 in diffys run for 50k or better.
 
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Originally Posted By: Steve S
Per my wifes uoa on Redline I am underwhelmed with Redline gear oil.
Good, more for the rest of us who like it.
 
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Originally Posted By: MolaKule
I also noticed you have a high silicon content. Now Redline does use a lot of anti-foam, but this seems high.
RTV from diff cover?
 
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Originally Posted By: AzFireGuy79
What do you use now steve? Amsoil SVG like the rest of this board???? grin LOL
Chevron DELO ESI.
 
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ALWAYS send off a VIRGIN sample of oil this is the only way to even get a accurate UOA. RL used silicon af but you have no way to know anything unless a VOA is sent along bruce
 
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I am not a fan of groupthink ... but Amsoil Severe Gear is a solid performer and a worthy (not at all laughable) choice. "Chevron DELO ESI." Another good choice ... going to do a UOA on it?
 
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