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[booster]

Originally Posted by Roadtreker357

Our 2007 C210 Roadtrek calls for 75W-90 gear oil. Looking for some guidance.

Looking at Red Line, I see there is also 75W-140 gear oil.
Which would be better lubrication to prevent this type of axle failure?

I also see several different Red Line offerings.
Synthetic Heavy Shockproof gear oil, 75W-90, #58204
GL-5 transmission and gear oil, 75W-90, limited slip, #57904
GL-5 transmission and gear oil, 75W-140, #57914
And other offerings

Which gear oil is considered the best to use for my application?
How much is needed to completely drain and refill the differential?

That is a very good question and I had the same question a short time ago.


For quite a while the manufacturers and oil makers were saying that if the axle was designed for 75W90 to use that in a top end synthetic. It is what I have been using.


But now I see that the vehicle OEMs have switched to recommending the 75W140 for the same, or same design, axles. My guess is that they were getting into high bearing temp issues so the higher viscosity when hot would help. These axles when originally designed were specified for much lower loads, and now they are pushing the limits way higher so that they might get wheel bearing overheating in a semifloater makes complete sense to me.


An overheated/failed wheel bearing or damage from a previous episode is probably what caused the axle failure for the OP of this thread.

I don't think you could go wrong with the 75W140 for a semi floating rear axle, but good 75W90 may be just as good, but now I wonder a bit about that.

[rstl99]

I'd go with recommended grade 75W90, unless you have a reason not to do so.

Your van owner's manual (or certainly the shop manual if you can get one, not a bad idea, I ordered one for mine) will indicate the amount of oil needed to refill the diff. Around 2L for my Dodge, I thought it would have been more. Haven't replaced the oil yet, would have done so by now but getting on in age and the water tank behind the diff will make the job a bit challenging for me.

Again, your manual should tell you what kind of oil is required (non slip or not). Your dealer may also be able to help you figure out the oil type and volume.