Differential oil -- Amsoil?

[crooper]

I've been reading on here for the past couple of days about changing the differential and transfer case oil. It seems like a good idea, since my 2008 V6 4x4 has almost 50k miles on it. I've seen that many people use Amsoil Severe 75w90. I'm just wondering about whether this is okay concerning my warranty -- since it seems using the Amsoil engine oil voids the warranty. Is the Amsoil synthetic much better than Mobil 1? I've used Mobil 1 engine oil since I bought the truck at 13k miles.

I'm hoping that changing the diff oil will reduce the clunking and the fact that the transfer case often takes its sweet time changing between to 2wd and 4wd.

 

[CJ3Flyr]

I've been reading on here for the past couple of days about changing the differential and transfer case oil. It seems like a good idea, since my 2008 V6 4x4 has almost 50k miles on it. I've seen that many people use Amsoil Severe 75w90. I'm just wondering about whether this is okay concerning my warranty -- since it seems using the Amsoil engine oil voids the warranty. Is the Amsoil synthetic much better than Mobil 1? I've used Mobil 1 engine oil since I bought the truck at 13k miles.

I'm hoping that changing the diff oil will reduce the clunking and the fact that the transfer case often takes its sweet time changing between to 2wd and 4wd.

I use the Amsoil with good results. Many use M1 too. The warranty thing is interesting, I understand both sides. (FWIW, I don't Amsoil my engine.)

The shifting time and clunk may improve somewhat. It won't go away. I say change the fluid! Use M1 if you are more comfortable.

 

[Merle]

I actually went with a synthetic put out by Shell for truckers. Supposed to have a 100,000 mile warranty or other such nonsense. But met all the specs and I didn't have to use anything (e.g. additives or friction modifiers) else for "tight" diffs/transmissions.

It's Shell Spirax S (Shell Lubricants in the USA - Products) and cost me (I think) $120 for 5 gallons of the stuff a few years back.

Yeah, it comes in a paint bucket sized container. But pretty good in the cars (e.g. Infiniti, Toyota) I've had w/o issues.