Differential Oil Brand

I would love to use synthetic but I just bought my truck with 122k miles so if I was to put synthetic I would probably need to replace the seals which I don't feel like doing also I'm not sure if mine has LSD it sure doesn't have the sticker although It does have a RR Diff Lock button so I'm guessing its an open diff thus leading me to believe I don't need the LSD additive am I correct? anyways which brand should I go with and while we're at it which brand of tranny oil should I use I was thinking of also replacing that. Thanks for your priceless input



The guy at autozone recommended lucas but idk.

 

I use the Lucas Oil synthetic.

 

diff lock is completely different than limmited slip differential you do not need the special additive for LSD I like mobile one 75/90 but I also like the lucas I think its 80/90 I use synthetic and never had to replace seals they say synthetics have so many seal conditioners that it can cause them to swell which creates leaks I never had a problem but I buy trucks that have been taken care of if anything already leaks I probobly wouldnt use it. being that you only change diffs and trans verry seldomely spend the extra cash and get something good ill say mobil one being its made for this application.

 

Synthetic, non synthetic who gives a crap. It's a bunch of bs when it comes to differentials. Chances are, you won't be able to put non synthetic to the test because I never have in my rear differentials either. Offroad to street save yourself some money and stick with the cheap.

 

Nothing wrong with synthetic other than it being $11/qt and smelling like dead fish.

No need to change seals.
If they leak with synthetic, they were going to leak anyways.

 

Thnks for the help guys I have a better idea now of what to get Happy Thanksgiving to all

 

Think I'm going with MB1 but they already have LS in it....shouldn't matter either way with e-locker right? May go with the cheapest but already have MB1 engine oil for my synthetic switch over!

 

I just go with Valvoline and change it out every 15,000 miles.

 

ECGS recommends Lucas, so I use Lucas.

Bump up to 85/140 weight if you're gonna use the diff like you mean it. If it's just street driving go with 75/90 or 80/90.

 

Is the 140 just thicker and handles the abuse better?

 

Same as motor oil.
Higher film strength, will perform better under high temperatures and higher load.
Moderately poorer performance when cold, may not lubricate the wheel bearings as well, but I don't think that's an issue unless you live in a climate that gets into freezing.

 

i put mobil 1 in my 09 prerunner.seemed noisier to me so i put conventional back in.i didn't see any gain in mileage.1 way or the other

 

Synthetic in the differentials shouldn't affect mileage one bit. Oil weight might.

In the original post, I use the Valvoline Synthetic in the gray container, lower left corner.