the owners manual calls for 75w-90 in a synthetic gear oil , previous change was w/ MOBIL 1 75w-90 at about 26,000 miles and currently has about 76,000 since the MOBIL 1 ( hope that wasn't to long an interval ) . So , I ordered REDLINE MT 90 75w-90 synthetic from local auto parts store . Hopefully didn't order wrong product ( other being MTL ) .