Which gear oil

[grego37]

Im about to put my 3rd member back in, which gear oil is the best.

It has a Locker, and is in a street car.

thanks.

 

[rbohm]

any good synthetic oil will do fine. royal purple seems to be popular right now, but i still like the old stand by pennzoil. as far as weight goes, 75W90.

 

[fasttback]

I ran Redline synthetic 75w-90 with some additional friction modifier in my 9" w/ trac-loc. Works fine, but synthetic oils (as I have learned) are more prone to leak than conventional oils.

 

[rbohm]

I ran Redline synthetic 75w-90 with some additional friction modifier in my 9" w/ trac-loc. Works fine, but synthetic oils (as I have learned) are more prone to leak than conventional oils.

actually when you switch to synthetic oil and have a leak pop up, the leak was already there, just plugged up with sludge.

 

[milner351]

As I recall you don't need to use the friction modifier with the locker, sinc it's mechanical / sprag lock, not friction disc lock like the trac-lock.....

correct?

Another vote for synthetic gear lube here. Valvoline, Amzoil, whatever you can get off the shelf, 80-90w or 75-140w.

 

[grego37]

Correct no friction modifier with a locker.

UPDATE:

I called Currie Enterprises , they highly reccomend NOT to use synthetic in the rear end. They said that the Ford 9 inch it has more hypoid angle than other rear ends (or something to that nature) I guess its the angle that is on the gears,and the synthetic doesnt work as well as non-synthetic in this case. They also said to run 75/140 wt.

Im going to take their word on this one and use 75/140 conventional gear oil, with no additives.
I can smell it already.

thanks for the feedback

 

[1969mach1351]

Anything already listed is fine. The shop I got my locker from had me use Valvoline 75w 90 which I believe is synthetic.

 

[thehueypilot]

They "Currie" told me the same thing and that my case was leaking because I was running synthetic gear oil. I ignored them and ran it anyway but went with 140 wgt synthetic. I took it apart last month to change out the gears from 4:11 to 3:55 and the leak was a chunk missing out of the pinion support which took a chunk out of the o-ring that seals the case. Someone at Currie dropped it on the floor and slapped it togather. Great Quality...