3 different brands, Same weight gear oil in the diff!

[zugdud]

Howdy all, well I drained and filled my diff tonight...(GM 8.5" 10bolt 30 spline axles with Eaton Posi) and had more spills then usual and added so I ended up being short of fluid. What I have in there right now is about a quart of 80-90 Pennzoil, a quart of 80-90 Castrol, and a quart of 80-90 GM. Plus a bottle of GM limited slip additive

Any harm in me driving the car for a week or two until before changing the fluid? If thats even necessary... The weight is the same, none of the oils were synthetic and the bottles even had similar marketing jargon

. Just not sure if the brands mixing will cause issues or not

Thanks!

 

[jthorner]

All of the modern gear oils of a given classification are supposed to be compatible with one another, so I don't think you are doing any harm.

For peace of mind you might want to change it out for a uniform fill at some point, but I would not be loosing sleep over it if they were all the same category oil.

John

 

[Eddie]

Most owners manuals warn you NOT to mix brands of gear oil because: of different additive packages may interact causing problems. So get the mix out.

 

[Pablo]

A week? No problem.

Life? Why risk it?

Just think of it as a rinse......

 

[zugdud]

Thanks for the follow ups, well I drove it today for about 50 miles to work and a few stops afterwards. Seems fine, no noise and temps are normal (I have a temp sending unit to the pumpkin)

Going to go change it anyway though as soon as I get the chance

 

[MolaKule]

As long as they are all GL5 rated, the mix shouldn't be a problem since they are dinos.

All the dinos have approx. the same type and amount of EP package.

 

[c502cid]

quit worrying, it's a rear end. No combustion, clean oil, posi lube added....Many rear ends go a lifetime with oil never being changed. No worries, leave it in. The additive clash crews here sometimes get a little worked up

 

[oilcan]

Why mess with regular gear oils in rear ends? Have Pablo send you some Amsoil and forget about it. Besides Chevy is running synthetics in most of if not all their newer trucks. My wife's 04 Trailblazer has synthetics in both front and rear diff. from Chevrolet.

 

[zugdud]

Well I already changed the diff fluid again, used standard 80-90 valvoline. Haha, mabey it was a wasted effort but after investing $800 in a new rear end im not going to screw around

I'm running an Eaton Posi in my rearend (non stock carrier in a 1996 buick station wagon), The Eaton uses clutches and from what i've heard, perform worse with synthetic oil, for whatever reason. GM trucks use a different carrier (Auburn i think?) or have an open rear if they are getting factory syn fills. Eaton tells all its customers to NEVER run syn fluid with their carriers, which is good enough for me. Their warrenty policy on failed units (that have traces of syn fluid) is too bad, so sad, we told you so.

[ October 28, 2004, 12:17 AM: Message edited by: zugdud ]