best tranny fluid?

[tommyinla]

no... a friction modifier is an additive that is added on top of the synthetic fluid; it is specifically engineered to allow smoother shifts than a regular (non-synthetic) fluid will allow. this modifier was designed for an automatic transmission so that the clutch mechanism would provide for smoother shifts... a friction modifier isn't good in a t5 because it won't allow the blocker rings (part of the synchronizer assembly) to grab the gear in order to slow it down or speed it up the way that it should, which would result in a harder shift.

the true benefit of synthetic fluid is that it will allow a longer service interval before you need to drain and refill the fluid in your tranny (which should be done about once a year with conventional fluids). of course, it's also a superior lubricant since the molecular structure is much more stable than a conventional fluid...

synthetic fluid will also cause your transmission to be just slightly louder than a conventional fluid.