Hey guys,

I'm trying to figure out what viscosity fluid to use for my fresh Puddymod diff. I want to go with Amsoil severe gear. Puddy recommends the 75W-140 but a friend of mine who is also a dealer and well versed in Amsoil products tells me that the 75W-90 will work just fine. He sent me the spec sheet for the three sever gear viscosities (90, 110, 140) and noted that the flash point and pour point were very close between the three.

http://www.amsoil.com/lit/databulletins/g2043.pdf

Would switching to the 110 really only decrease fuel mileage slightly? I just find it strange that between the two experts there are different recommendations.

 

Ben is pretty adamant about using the 140 for his diff. I suppose that will be what I use then.

 

Matt that's what I picked up also to use after my break in.

 

The 90 is perfectly fine. The 140 will provide more "cushion" and maybe that's why puddymod wants you to run that for added protection? I've ran 90 in both stock and ford 8.8 diff 700whp and it's fine. You can't go wrong with either one imo.

 

Josh are you running something different for the break in?

Slow, I suppose so. I'm going to go with the Ben's recommendation.

 

Yeah Matt Ben will email u break in directions. I'm using a reg diff fluid not synthetic for the 1st 500 miles of easy light driving, then put in the amsoil take it easy for 300 miles then good to go. I just put Valvoline forget the weight in for break in.

 

I already got amsoil sever gear and planned to use that for the break in as well. Is that a problem?

 

Ben told me to use a regular non synthetic for break in. Then go to the 140.

 

Cool thanks. Ben told me that the amsoil synthetic is fine for break in. If rather just use what I have instead of going out to the store again lol

 

I run the Amsoil 75w-140 in my Stage 1.5. No issues.