I picked this up with the intention of changing the rear-end fluid and found this on the mobil site

• Mobil 1 Synthetic Gear Lubricant LS 75W-140 is recommended for use in modern high performance vehicles like sport utility vehicles , vans and light duty trucks requiring API GL-5 performance that require excellent durability
• Mobil 1 Synthetic Gear Lubricant LS 75W-140 is intended for initial fill, topping-off or refilling differentials, final drives, transfer cases and other gear applications where lubricants meeting API Service GL-5 and multi-purpose or mild EP gear lubricants are recommended
• Mobil 1 Synthetic Gear Lubricant LS 75W-140 can also be used in rear axles where API Service GL-4 lubricant is recommended
• Not recommended for automatic, manual or semiautomatic transmissions for which engine oil or automatic transmission fluids are recommended
• Recommended for many limited slip applications. For certain high level LS applications, additional limited slip additive may be required if axle chatter is observed.

was wondering if anyone has tried it yet, goodness this stuff is expensive though, 18 dollars a qt at my local auto store, i imagine it doesn't require the additive for the LS

also would it hurt to use this in my front differential. I know the manual say 75w-90w for the front but would it hurt to use this in there as well?

thanks

 

I've got 5 or 6 qts in my rear end with a mag-hytec cover. I did not have to add any friction modifier and I have no chatter or sliping seems to have the perfect amount of friction modifier blended with the oil. In my opinon Mobil 1 makes good quality lubes but you might also look for amsoil I think you can order for a few bucks cheaper. As far as the front end goes I havn't tore into it based on the fact that I don't use the 4x4 alot. Enjoy!!

 

I'm using it in my trutrac, which was supposed to be 80/90 and I've had absolutely NO problems with it. Dif is as quiet as a mouse. 40K miles on this run.

 

Mobil 1 is a great product.

I'm an Amsoil prefered customer, and went with Amsoil. No friction additive was added. My limited slip differential is tighter now, which is fine by me.

If you go to the Amsoil.com website, they have a gear lube test done on all the major suppliers out there. Guess who came out on top? Amsoil of course, otherwise they wouldn't publish how great they are.

 

I read it and I posted about it in this forum. They picked the results they wanted everyone to see and they published it. Of course they came out on top. Doesn't mean it's the "best" out there. More typical Scamsoil marketing practices.

 

I run it in my rear diff, changed after the 08 cover swap. I found out after that Royal Purple is @ half the price and I hear it is very good, FWIW. Don't know about the front, though.

 

I changed it today, no modifier needed it runs fine with no chatter. I can't believe the manual says to run it so long between changes, that fluid was black!
then I lubed the drive shaft splines. what a pita the driveshaft is by yourself. I guarantee i will be faster the second go around.
then again it was like 90 out today with no clouds on a asphalt driveway., man i think the sweat and heat beat me up more than the work.

 

My rear oil came out like a chocolate milkshake last week, probably because of the clutch material on the LS unit. Ford overrates everything, Engine oil changes, rear oil changes, and engine coolant.