Black on blacK

my rear differential was leaking oil so i took it to the shop to have it filled back up and they said it had been filled up too much last time and that's why it was leaking. i asked them to change out the oil that was in there but they couldnt figure out whether or not to use synthetic or regular. i had 4.10's put in but i didnt kno if my gear ring changed with the gears. anybody kno whether i need synthetic or regular oil for the rear differential with 4.10's of a 2001 bullitt?

ShadowDrake

Tag on my differential says synthetic 75w140 only... As long as you're close it'll be ok. Either type of oil will work, but I would go with synthetic either way.

DON'T FORGET FRICTION MODIFIER!

Black on blacK

all right thanks man