Synthetic Oil in Rear Diff of a P32

RocketDork · 03-01-2010, 11:29 AM

Do any of you see a problem with moving from the Dino Oil to Synthetic (other than cost) in the rear diff of a P32 Chassis? Anything I should be aware of or do if I make the switch?

dieselclacker · 03-01-2010, 11:50 AM

Quote:

Originally Posted by RocketDork

Do any of you see a problem with moving from the Dino Oil to Synthetic (other than cost) in the rear diff of a P32 Chassis? Anything I should be aware of or do if I make the switch?

Just make sure you re-install the correct amount, and the proper grade (viscosity) of synthetic, and you should have no problems. New Workhorse chassis come with synthetic in the differential, and have for several years.

Dieselclacker

RocketDork · 03-01-2010, 12:13 PM

I just wasn't sure if I'd have to clean the old lube out or if there were any incompatibilities...

lyledavid · 03-01-2010, 05:01 PM

Rocket.
After changing from Dino oil to synthetic you may have problems with wheel seals and the input shaft seal. There is a build up of the dino oil under the seal lips and the synthetic will clean this build up at the seal lips and may cause them to leak or weep,
Thirty-six years in the truck axle and transmission field taught me this.
lyledavid

RocketDork · 03-01-2010, 05:22 PM

How long does it take for this build up to build up? My coach has about 40K miles on it, and is 10 years old...I'd hate to have to replace seals just because I change oil types.

DAN L · 03-02-2010, 05:04 AM

Quote:

Originally Posted by RocketDork

Do any of you see a problem with moving from the Dino Oil to Synthetic (other than cost) in the rear diff of a P32 Chassis? Anything I should be aware of or do if I make the switch?

my workhorse chassis manual on page 94 states this:
''sae 80w90 gl-5 axle lubricant for 1999 and 2000 chassis vin y3325061 or lower. all other chassis utilize synthetic gear lubricant sae 75w90 gl-5 emgard2984 pn 12345841."
imo you could probably upgrade to synthetic if you want to, as long as it gl-5 rated.