synthetic oil in older newell rear end

[Newell Attack]

does any body run synthetic oil in there rear end? I don't know if it would hurt a older rear end or not.

Jeff



How about running partial or full synthetic gear oil in a bus conversion or luxury motorcoach rearend or differential? Would this be feasible whether or not the custom motorhome was an older or later model unit? Do certain manufacturers recommend for or against synthetics on larger vehicle's?

[77newell]

Hey Jeff: I've been running synthetic oil in my rear axle, I try to keep my rear end away from oil for obvious reasons, for close to 10 years. I had new axle seals installed at the time the synthetic was installed. It didn't even occur to me that there could be a problem and so far there hasn't.

[Neweller]

From everything I have heard speaking with bus and motorhome DP mechanics, you can definitely run synthetics in your differential rear-end and Allison automatics.

Surprisingly with synthetics in a differential, Rockwell is showing what appears to be a GL-4 50W Transmission Fluid which would appear to be much lighter than a standard 80/90W gear oil. In all actuality transmission fluid viscosity is measured differently than differential oil.


This is what is currently recommended:

Rockwell Differential. 3.58 Ratio - Delvac Synthetic Transmission Fluid 50w Part# MBL 98HL93
Allison HT-755CR - Delvac Transmission Synthetic Fluid Part# 27101-CTCS

Something I would highly consider when switching over to the synthetics is replacing your seals. There have been problems with older seals leaking when switching to the thinner higher lubricating synthetics.

[Gone Busing]

Prior to the purchase of our bus it had already been upgraded to synthetics and we have never had any kind of issues with it and the oil samples always test out good. Not how much of a real difference it makes but we have Redline in ours.

[86loco]

Hi Jon or Jay, are either of you picking up any mileage gains with the use of synthetic oils?

[77newell]

Hey Brady: that was part of what I had in mind. The problem is I did it right after the purchase so I have no comparison.