I just switched to Mobil 1 synthetic ATF around 187.5 K miles. I'm still on the first week so it's too early for any long term opinions, but I have put about 500 miles on the tranny since changing to synth ATF.

Shifts are definitely smoother in everyday driving. It seems to take less warm-up time to shift smoothly. Slippage after shifting from R to D I still have, but not as frequently. I still have a brief lag going from R to D or vice versa.

All these things seem better, but maybe (and this drives me nuts after every shift that's a bit firmer than most) it's psychological...you know, trying to reassure myself that paying $4.99 a quart for ATF that is <$1 at BJ's or Sam's is really worth it, but I'd say YES definitely. Re: the question of where to get it?, I found it at Pep Boys, AutoZone, and Advance Auto Parts. All but the latter were $5.99. Advance was $4.99. This was last summer, so don't hold me to it. I had been adding synthetic as my fluid level dropped, but finally convinced my wife and my mechanic that it might be a good idea to change my ATF way before it had to be

To summarize, I've never had such smooth shifting, especially after the drivetrain has warmed up. Now I'm rethinking the synthetic oil question too...

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Bob Roe
Lehigh Valley PA USA
1973 Olds 88, 1972 MB 280SE, 1978 Datsun 280Z, 1971 Ford T-Bird, 1972 Olds 88, 1983 Nissan Sentra, 1985 Sentra, 1973 230.6, 1990 Acura Integra, 1991 Volvo 940GLE wagon, 1983 300SD, 1984 300SD, 1995 Subaru Legacy L wagon, 2002 Mountaineer, 1991 300TE wagon, 2008 Murano, 2007 R320CDI 4Matic 52K, some Hyundai, 2008 BMW 535xi wagon, all gone... currently
2007 Honda Odyssey Touring, 2014 E350 4matic