I've had Auto-Rx in my Olds minivan for 1500 miles and now I'm about to begin the 2000 mile "first rinse." I've decided to use a 5w20 oil for the rinse. The main reason I chose a 5w20 is I want a thinner oil that will get to all the little nooks and crannies of the top end. I think I'll only be the second person on here who is trying a 5w20 in a vehicle that orginally called for an Xw30 oil. (TooSlick tried the Amsoil Grp III 5w20 in his truck, if I remember correctly.) Even though this oil will only be run for 2000 miles, it will probably take 6 months to accumulate that mileage, so I'll be doing a UOA on it next spring. I picked up a 5 qt jug of Pennzoil 5w20 tonight at Wal-Mart for around $9.00. I wanted a 5w20 that had lots of moly, so that's why I picked Pennzoil over the Motorcraft (even thought the Motorcraft 5w20 has posted some outstanding UOAs). I was a bit surprised, however, to note that nowhere on the Pennzoil bottle does it say this oil meets the Ford and Honda requirements for a 5w20. One would have to assume it does, though.