I have a 2000 Yamaha Big Bear 400 4x4. I'm going to change my front and rear differential fluid. The last time I changed it I went with Yamaha diff fluid. I want to switch to synthetic fluid this time. I plow and haul firewood with it. I don't beat it, I do however work it pretty hard sometimes.

I was going to use Amsoil Severe Gear 75W-90. I was going to use this for three reasons, 1- I have more then enough left over from my truck, 2- it works with limited slip diff's (my front), 3- I use their 0W-40 synthetic oil and their Superduty oil filter. Amsoil recommends I use their Universal Synthetic Marine Gear Lube because it works good if water gets inside. I've never had any problems with water getting inside my diff's.

What are you guys/gals using for diff fluid?

Thanks, NYH1.

 

I use the Yama gear lube (80/90)... Its always a good idea to stick with whats in it, but it wouldnt hurt to use the Amsoil.

 

If its "Full" synthetic(NOT RIP OFF BLENDS) its better stuff than dinosaurs remains,grease,motor oil of Gear oil without a doubt. Search goggle "Synthetic VS Conventional" and you will read all day long that Synthetic is Superior to conventional in every way but price.

There are some "blends" out there that cost as much as Full synthetics and are lucky to have 10% sythetics in them,Yamalube and Honda GN4 are a good example.

 

I run a Polaris which calls for different fluid in the front then the back. but I haved use Amsioil 75-90 innthe rear since 2004 and have never had a problem.

 

the case on my 99 big bear was stamped 80w90 SAE.