2000 Differential Fluid Question

Hello all again,

I know that the rear diff uses 75-90 synthetic and the front 80-90 Regular GL5 but...

1. If I have a locking rear axle (G80 code I think) I don't need any additive on top of the synthetic lube, correct?

1. In the front I used a lube that said it was "suitable for limited slip differentials." Does it matter if I use a 80-90 that can be used in limited clip applications for the front diff?

Thanks in advance, I just want to check for sure,

Clint