hi! ive got a ford 4.0 sohc 300k miles. would you reccomend switching from the factory 5-30 to a 0-30? Ive found some but none in the HM flavor. would you reccomend switching to a 5-40 or 0-40 too? theres a couple monor leaks so thats why i use HM. also ive heard sometimes diesel oil is good...
