neighbor got a 2007 1500 Chevy 4.3, rough shape, but runs good with 155k miles. His dad has a ton of rotella T5 10W30, would it be ok to run it in his truck for 5k intervals? I heard something about diesel oils can soften the bearings or metals in a gas engine? I might just dump in the jug of Mobil 1 0W40 Euro in it that i have sitting around with no use for, i dont think it would hurt it. His dad has a '94 chevy with the 4.3 i noticed that truck takes a napa gold 1036, while the '07 takes a 1040, which is shorter. same specs except for the length, so it shouldnt hurt to use the longer 1036? They wanna buy a case of filters and be done with it.