First off, this site is a fantastic wealth of information - in some cases an overwhelming amount of information , so before I ask for your advice, I'd like to give out some basic stats on my situation: I'm the 2nd owner of a 1997 Cadillac Sedan Deville, 94,500 miles, Northstar engine. Never been opened up, never had any head work, just your standard fluid change-outs. I do this every 4,500 miles. 9,000 miles ago I switched to MOBIL 1 synthetic 10W30 for the engine c/w K&N oil filter and MOBIL 1 synthetic ATF for the tranny. The car is stored for the winters. As an aside, I have another Caddy (1988) that gets the winter driving duties and it's innards are regularly bathed (every 4,00 miles or so) in 10W30 oil and has had Slick 50 treatments, with no appreciable detriments or benefits. For the '97 however, I'd like to be a bit more proactive and protective of it's current rosy condition. I plan on keeping the '97 for many, many, years. This car runs like the day it was bought off the lot, never had any issues with the drivetrain at all (and want to keep it that way). Regarding the mileage however, I think that I should now be adding something else into this mix ie; oil and tranny additives - just in case. Now for the big question: Bearing in mind all the above info, what, in the opinion of this board would be my best bet re: additives? To just read all the info (and it is really golden info, believe me), there must be hundreds and hundreds of lotions and potions out there. But for a regular guy, with a regular steed, that just wants to keep that steed in the best shape it can be for as long as it can be, is there one brand above all the others that you'd recommend? I have no pre-conceived notions or bias towards any of them, just want some peace-of-mind-in-a-bottle - if indeed one exists out there. Thanks in advance for any and all considerations, guys.