We change oil & filter in all our gasoline engine vehicles @ 3000 mis (approximately). They're all now equipped w/oil quick-drains so it's not hard to do. Not much (if anything) to grease anymore unless they're 4wd. Filters can be messy-I've always wished there were better engineering on filter access for changing reasons.

I'm not saying this is right or wrong, but it works for us. Never had any failure due to oiling problems. But then again, there may be someone that changes only @ 50,000 mis who can say the same.