Was wondering if there are any negative effects if one was to mix different gear lube weights? Like I need 1.8qt of 80W-90 and only had 1.5qts of 80W-90, can I fill the rest with 75W-90 if I can't find any more tomorrow? I probably should have just used the 75W-90 instead? This is for the rear diff on my Tacoma.
I've added 2 gallons of 85w-140 to 1 gallon of 80w-90 and run it in my SM420, and rear end of my 40. It quieted the SM420 down significantly. It didn't make any other difference that I could detect.
I change fluids after every major dunking, so I don't think it will be in there long.
