Switching to Synthetic ATF with high mile trans
I've got a 1994 C220 with 120K miles and would like to switch to Mobil-1 Synthetic ATF Fluid. It seems the benefits outweigh the price tag. I am currently running Castrol Dexron III ATF Fluid. One reason for the switch over is that I can't stand the 2-3 upshift delay when the C220 is cold, but I suspect synthetic ATF won't help this.
A good friend of mine, a BMW mechanic, does not recommend switching over the Synthetic ATF with high mileage transmission (More than 60K) because he claims (at least with BMWs) that he has seen a lot of failures happen after the switch over. He believes that the detergents with the Synthetic ATF do too good of a job - loosening crud that eventually causes a failure.
Any thoughts on switching over on a car with 120K miles?
Also, when I drained/refilled the transmission (no torque converter)...I was only able to get 2.5 quarts of Castrol ATF into the transmission - I think it's underfilled, but the dip stick says otherwise. If I switch over how many quarts will I need (esp. after I drain the torque converter).
1994 C220 (another one with a bad wiring harness!)