been running 5w30, but i have enough of royal purple 10w30(acquired it from my grandpa who was friends with the owner/founder of RP) to do the next oil change.
i am trying to be frugal and use what i have, is there any reason i shouldnt use 10w30?
about 18k miles on a 4.0L
driving conditions for this next oil change will be extreme highway miles (800+ miles at a time) as well as offroading when i start my road trip.
rather than start a new thread... i also have 75w90 RP gear oil, should be good to go for front/rear diffs correct? (e locker rear) TRD O/R