Just bought a Suzuki Grand Vitara 2006 that is RWD with 130k. About to change out the diff oil. I have some left over bottles of 75w90 NS Redline that I could use and it is GL-5. However, these were designed for manual transmissions and not optimized for diffs like their regular 75w90. What do you guys think? Pony up the $20 for the normal diff oil or just use the perfectly good oil I have?