my friend wants to do a gear install like i did in his 98 cobra and switch to 4.10s, i used royal purple in my 96 with the friction modifier but he wants to just use mobil 1 synthetic w/o the friction modifier, i think this is a bad idea but he wont listen to me lol, i had to order my gear oil cause no one around here sells royal purple. I think thats why he just wants to use the mobil 1 w/o friction modifier. Hes doin the install tomorrow with me and my uncle, what do you guys think will this work? I dont want to help him install it and then his gears fail, esp on a cobra.