Does a TRD rear axle need a friction modifier?

I bought a first gen recently that has the rear e-locker. The PO had one of the rear axle bearings replaced recently and when he did, the shop put a friction modifier in the rear when they filled it.

I think the rear is all stock and is an open diff. But the mechanic told the PO that it needed the modifier.

Is that true? Was the mechanic mistaken? If it's an open diff, will leaving it in there hurt it? I will jack it up and spin the wheels when I get a jack tall enough, but in the mean time, can someone answer the question?

I'm planning on doing all the fluids this week and am wondering if I should change the rear diff out too. And if so, do I need to add any modifiers for the e-locker?

Is synthetic okay, or is it too thin?

 

Locker don't need it. You can leave it in, won't hurt nothing.

 

no an elocker does not use friction modifier

 

Thanks guys. That's what I thought, I just wasn't sure. I think I might just change it out anyway, since I'll be under there changing everything else. Who knows what kind of oil they put in it? He obviously made an error with the additive.

Is synthetic okay for the rear or is it too thin? I have the FSM and it says:
Hypoid, GL5, 75-90W

But it also says that for the transfer case and I thought the T-case was to use GL4? I've encountered misprints in the FSM before.

Is that right? Hypoid, GL5, 75-90? Or something else? Synthetic okay? The amsoil page recommends sever gear AND their "gear lube" additive.

 

You won't find 75w90 very easily. Just use any 80w90.
If the gear oil in it is new then no reason to change unless you're bored. Dino oil for the diff is fine.

 

only lsd needs a friction additive

 

Hi Guys - I am just getting ready to change the Front Diff, Transfer case, and Rear Diff on my 2010 TRD Sport. I was told the 2009 and up do not use the LSD in the diff anymore and are controlled independent? I am looking at 75W90 Amsoil Severe Gear for all of these and would like to know if this is the way to go? and can someone confirm that I dont need the LSD additive due to the change on these later models with the LSD setup? what are peoples thoughts on Royal Purple vs Amsoil?

Thanks!

 

Probably better off asking the guys in the 2nd gen forum. They are more knowledgeable about the 2005+ trucks.