What is the relationship (generally speaking) between film strength, film thickness, and viscosity: If I polish / superfinish the gear teeth, and bearings on trans, can I go with a lighter viscosity oil, to improve the efficiency of a manual transmission, while still keeping reasonable safety margins? The gains: http://www.remchem.com/cms/index.php?page_id=2 The process: http://www.remchem.com/cms/index.php?id=9 I keep seeing advertisements stating things like 'synthetic oils have 5x the films strength of conventional oils...' I know this doesn't mean I can run an oil that is 1/5 the weight (assuming that amsoil's claims are correct), but how much lighter of an oil could I run, using a quality synthetic? Especially if I go through the trouble of superfinishing the gear teeth, and bearing races. The trans this is going in calls for ATF fluid. It is for an old Ford Taurus SHO.