What Synthetic Gear Lube do you guys prefer for the rear diff?

 

I ended up using Amsoil and a bottle of their friction modifier. It was close to the same price as everything else and the local dealer is close to me. He had everything in stock that I needed.

 

Valvoline.

But anything with a friction modifier (if you have a limited slip) will do.

 

I use Mobil 1. IIRC, it has friction modifiers in it, but I don't really need them with my Truetrac.

 

I've tested two different brands in my F-250. Royal Purple and Schaeffer's 75W-140. Wasn't very happy with the UOA reports on the Royal Purple - the viscosity sheared down and the iron wear was much higher than compared to the Schaeffer's UOA. Most of the miles were towing.

Royal Purple UOA



Schaeffer UOA

 

Thanks Guys, Hey Rich thanks for posting those UAs good info. Just for giggles lets keep this going post up what Gear Lube you put in your differential when you did a lube change.

 

Mobil 1.

Pop

 

I tend to use a lot of the Mobil 1 products, Mobil 1 is in the rear, but Front has Motive Gear because it was all I could find of quality locally at the time.

 

I like to use Mobil 1. How many remember their commercial where they hammered a nail with a banana @ -30F? then poured their oil.

 

Another vote for Mobil one. I added some modifier, someone told me that it needs a bit more to meet Ford Recomendations.

 

I have Red Line 75w-140, didn't need any FM, in the rear and Mobil 1 775w-90 in the front. Seems to work fine.

 

I also used the Redline. Got a gallon of it from Summit just in case I spilled some while filling, which I did...
Red Line Synthetic Oil 57915 - Red Line Synthetic Gear Oil - Overview - SummitRacing.com

 

I used Mobil 1 front and rear.

 

Valvoline in both diffs for me.

 

I used Valvoline SynPower. It had the friction modifier in it for the LS.