Ok, first off, sorry if this post gets long. Second, I'm a newb here and need some help/advise. I currently own 3 cars, an 02 Nissan Sentra Spec-V (5K miles), Nissan Xterra with 3.3L V-6 (89K), and a 93 Honda Civic 1.6L VTEC (62K). The Xterra and Civic get driven on a daily basis approx 85% city and 15% H-way. The Sentra is pretty much a weekend car that gets driven fairly "spiritedly". I live in Northern Va. with the usual weather extremes that go with this location, use Amoco 93 in all the cars and maintain them very well IMO. All of them, with the exception of the Sentra, have had Redline 5W-30, 10W-30, or a blend in between since after break-in. I arbitrarily set a drain interval at 5K and have never done any oil analysis. Since my Sentra is due for a change to synthetic, I'm wondering about going with RL or M1. Since I will now have 3 cars running synth, should I go with the M1 to save a few bucks or stay with the RL? I can get M1 for about $3.90/qt. versus $7.75/qt for the RL. I have been reading all the posts and following both VOAs and UOAs and it seems the M1 has some pretty good #s especially since they got the SS re-re-formulated with a barrier additive. I'm rather concerned about some of RL's #s that seem to indicate more wear (higher metals #s) than M1 under similar conditions. In nutshell, I'd like some pros and cons with my proposed choice. If I do switch, is it recommended that I Auto-Rx the other cars prior to a switch to M1? FYI, I have never had any oil related problems in any of the cars. Thanks for any advise.