I've been running Mobil 1 now since the late 70's, currently using 10W-30 in everything, now that I'm in Arizona. Used to use 5W-30 in NJ. I change the oil every 10K miles, or yearly, whichever comes first. Current cars, 98 Mk8, 2008 Expedition, and 1992 Cherokee don't leak, or burn any oil on...