My gf's 96 explorer has the ohv 4.0 in it and has 100,000miles on it. She bought it with 93,000miles on it and I changed oil 4,000miles ago with q.s. green bottle. My next change will be with valv. maxlife 5w30. My question is, I'd like to clean it out good, but she does mainly short trips, so I don't know if it would get driven hard enough for AutoRX to work. Could I maybe try some Rotella T syn. along with maybe a quart of MMO to clean it out good? If so, how long do I run it? I figured the RTS would be ok for use in the warmer summer months, what do you guys think?