Whining rear differential on a Subaru...very common. Dad-gum but AmSoil 75-90 quietened it significantly. So significantly, my 5 year old child noticed it. The fluid I drained was Specialty Formulations, and there was almost zero paste on the magnetic plug after 20,000 miles, so, I don't think the whine was a wear problem. Interestingly, the SF green dye had all but disappeared...it was almost as grey as the Factory fill.
Probably not a significant finding, but, I had to check to satisfy my question of a problem developing or not.
Re: 75-140, I put it in the differential of a 4.6 liter Ford, originally spec'd for 80-90. I only ran two tanks of gas through this used 04 car, so, I can't really say what the mpgs were, but, I've since run 5000 miles on this car the past month, and I'm averaging 26.5 mpg, mostly on the Highway, usually about 72-73 mph, with a few traffic stops, a few runs up to 90, a few quick starts, about 100 miles of actual city driving. It's rated at 25 mpg highway, so: short story is it can't be hurting the mpg much!
Probably not a significant finding, but, I had to check to satisfy my question of a problem developing or not.
Re: 75-140, I put it in the differential of a 4.6 liter Ford, originally spec'd for 80-90. I only ran two tanks of gas through this used 04 car, so, I can't really say what the mpgs were, but, I've since run 5000 miles on this car the past month, and I'm averaging 26.5 mpg, mostly on the Highway, usually about 72-73 mph, with a few traffic stops, a few runs up to 90, a few quick starts, about 100 miles of actual city driving. It's rated at 25 mpg highway, so: short story is it can't be hurting the mpg much!
