Rear end synthetic oil?
 

:confused: Has anyone used Amsoil? They say they are great, but I know nothing about them. I was thinking about using it in my rear end,trans, and motor! Amsoil says they are better than Mobil 1? If anyone has anything to say about Amsoil please help!

1999, F-150
5.4 L
auto trans

I have used both, and as frequently as I change fluids, I've not noticed any difference other than my wallet is alot lighter when I use Amsoil. I'm using the Mobil 1 now and it works great. I am not promoting either one, but I believe if you use quality products and change at proper (or even sooner) intervals, the normal driver (and vehicle) will be quite satisfied. Did you ever see the Consumer Reports taxi cab motor oil testing?

I am told you should not use the synthetic if you have a LS rear, so I haven't tried it there.

That is absolutely wrong. Your rear dif (LS or not) comes stock with syntheic oil. There is a tag right on the pan cover bolts that states that you should only use 75W-140 synthetic oil. If you have an LS dif add the Ford friction modifier even though Amsoil tells you you don't need it with their Series 2000 gear oils.

Thanks roden, I'll check it out. I haven't needed to change it yet, but I will very soon.

A lot of people use the amsoil in the rear end and I can't blame them.The ford synthetic goes for 17 bucks a quart at my local dealer......amsoil is cheaper and they do have a reputation for having a good quality product.I can't get amsoil locally so I run Redline synthetic in the rear end(and front end-4x4).they also have a fairy good reputation.........

Lightningcrashz, you can get Amsoil if you want to. Just dial
1-800-956-5695 7am-5pm Central time M-f.
I am not a dealer, but looking to use Amsoil myself.
Ask for a Factory Direct Catalog.

Synthetic oil
 

I just filled my rear diff with 85w-140. I am wondering if this lube might be to thick or not. I don't think so. Anyone else have any thoughts on it. It isn't a synthetic oil. I picked it up at our local retail store, kind of like a farm equipment place. They had 75w-90 in a synthetic, but nothing that went close to the 140 mark. I decided to fill the rear with the 4oz of friction modifer and the 85w-140.

I know
 

I could have amsoil delivered to my doorstep, if I wanted.I prefer having the option of running down to the parts house to get get it in case of an emergency ( example :my nice shiny chrome diff. cover started leaking and I don't have the time to take it off to redo the gasket,I will just keep checking the fluid level and add as necessary until I make time to fix it)

Oil
 

I have heard really good things about Redline Oils. according to the websight it will increase HP Give it a look I think it is Redline.com

I went with Redline 75w90 Synthetic. Have a look at my earlier post (diff oil change how-to).

My local parts store has tons of it. I hate mailorder so Amsoil is out.

FWIW 75W140 goes in the rear and 75W90 goes in front.
I have used both Redline and Amsoil and I can not feel a difference. I had the tranny out for a new clutch and we had to use dino oil in the T-case, I had Amsoil in it. My buddy has some Castrol synthetic ATF that I want to try. Cheaper than Redline & Amsoil.

Regards

Jean Marc Chartier