Amsoil in rear diff?

[jvencius]

If I'm going to put Amsoil synthetic gear lube in the rear diff of my truck (3.73LS), do I have to use friction modifier?

 

[CHPMustang]

If I'm going to put Amsoil synthetic gear lube in the rear diff of my truck (3.73LS), do I have to use friction modifier?

I've read of an instance or two that friction modifier was needed but overall it's not,speaking of that I have 5 quarts of the Amsoil ready to go in anyday

 

[_CH_]

as i recall the amsoil has some in it but even if not, the LS will still work. in fact if anything it will be more agressive - but wear out slightly faster.
not that its any great loss w/ the quality of the stock ford LS

 

[powerboatr]

bill
thats one in your face 2006

happy new year to you to


i was going to switch to sythetic as well but found out i already have in the 430
so we shall wait for a few more k miles

did the last set of receipts to gallons used and we are still averaging 15.5 and a cost of .16 per mile over here 10200 carefree miles

 

[DaveBen]

If I recall correctly, Ford does use syn oils in the differentials from the factory. I know you all are died in the wool Amsoil types, but I am not.

Dave

 

[powerboatr]

Dave
no wool dying here
castrol.
shell

 

[JimmyDee]

If I recall correctly, Ford does use syn oils in the differentials from the factory.
Dave

All the SDs have 75w140 synthetic in them from the factory. I put in Amsoil but it was only because I couldn't find any synthetic locally except at the Ford dealer and that was $19 a qt.
Jim

 

[jvencius]

If I recall correctly, Ford does use syn oils in the differentials from the factory. I know you all are died in the wool Amsoil types, but I am not.

Dave

Hmmm--I thought that they used synth fluid, but it's a really crappy grade of fluid and so it really isn't that much better than dino-sourced (pun MOST-definitely intended) fluid. I put Amsoil tranny fluid in my ZF-6 30K miles ago and there's no way I'd go back to Motorcraft fluid. Before, in cold weather it felt like I was shifting gears through concrete but after the swap shifts got smooth and easy.

 

[powerboatr]

jv
when i switched to Brand X synthetic in my 92 f250 is was like night and day difference the engine was smoother, the tranny was smoother and a few less noises.
mpg went up to 14 yep i know

firm believer in good syns. just not sure on a particle brand.
been waiting to get the truck broke in before we switch over
and i have read the syns in the 6.0 dont hold up well with shear. so the jury is still out on crankcase fluid

but if i ever find syn for the tranny its going in soon