rear diff gear oil weight for long trip...

Going to fl. f/ny and back. Not towing this time, but will have a lot of weight in the xj, plus twenty-hours straight driving.

Should I drop the standard weight Mobil 1 synth, and go to their heavier weight 75/140? Just installed new wheel bearings, fwiw...

Also, been using 10/30 religiously since new, again would a heavier oil be better? 117k on xj and runs as smooth as day one...

Thanks,

Mike, I think the M1 75W-90 is fine for the trip. Although I'd go up to the 75W-140 when towing.

I'd also stick with the 10W-30; it's fine unless the engine's using some oil.....
I use Castrol 10w-30 in mine.

the stock weight diff oil should be fine. i havent noticed any adverse effects when traveling in either of my vehicles.

I'd like to keep the stock oil, the M1 10w30 has been good to me, no oil usage. Motor runs perfect thus far.

Thanks, guys,,,