The parts sliding in the transmission and the rotating parts of an internal combustion engine are lubricated in fundamentally different ways. The shifting is as you describe, two metal surfaces sliding against one another with an extreme lubrication package (ZDDP, moly, graphite, sulfur) acting like tiny little ball bearings between them. Things like engine bearings (main bearings, rod bearings) cam lobes and almost everything else use hydrodynamic lubrication; the parts never actually touch. So an oil can be very good, excellent and even outstanding at one and lousy at the other at the same time. And in fact, as the same oil gets better at one, it almost always loses ground on the other one; ZDDP will actually <cause> an increase in wear in the hydrodynamic bearings if too much is used.
I doubt you are interested but I think I can give a quick overview of hydrodynamic lubrication while waiting for the A/C to take hold and before the wine takes hold.
Think of a crankshaft journal rotating inside a main bearing shell. The two surfaces are very smooth and very close- no more than 3 to 5 thousandths of an inch gap (diametral, not radial so it is 1/2 of that on either side). Now picture the oil that is in contact with the the crankshaft surface- it has virtually no movement relative to that crankshaft, which means it is moving at the same velocity as the crankshaft surface. But the oil in contact with the bearing shells also has no movement relative to the shells, which means that that oil is not moving, just as the bearing shell is not moving. So the film of oil that is only 1 or 2 thousandths of an inch thick has a gradient of velocity across it: one surface is not moving and the other surface is moving very rapidly. Now that gradient, where the oil is, and MUST, shear, has a pressure gradient in it as well, caused by those very shear forces. Those shear forces are all around the crankshaft and do not do anything for anyone other than to use power to shear the oil in the first place (which is why it gets hot). But here comes the key.... when we also push on the crankshaft, we knock it out of the center of the bearing, and the exact same amount of shearing force is now made up in a small gap..... which means there is less oil to shear and it must absorb more force where it is thinner (less oil having the same shear force means the oil must shear faster where the gap is less). That increase in shear forces pushes back on the crankshaft and viola! we have a hydrodynamic bearing. As the engine tries its best to push the crankshaft down (mostly down in a vertical engine), the shearing force increases and resists the crankshaft moving downward until the forces balance and the crankshaft is merrily spinning away, with TONS of force on it, literally, without ever touching the bottom of the bearing housing. If taken to extremes, as the oil film gets thinner, the forces increase until the chains of oil are forced out of the way (unlikely) or the oil simply gets so hot it vaporizes (likely) at which point a main bearing failure is almost inevitable.
The best analogy of a hydrodynamic bearing I have heard is that it works exactly like water skiing- the faster you go, the more force is generated and the less the skis sink in the water. The rotating part of the bearing is literally oil- skiing on top of the bearing shells.
Remember those old commercials for STP where the Sumo wrestler could not pick up the screwdriver once it was coated with STP thereby proving how slipper it was? Yeah, it does not and never did work like that and that 'test' was meaningless as far as showing the qualities of a motor oil.
Brian (cooler here now! where is my wine?)
Never to much info, just takes more effort to arrive at the correct conclusion(s). I am no engineer but all those tranny parts seem to me to require protection from high pressure metal to metal contact to preserve their useful life more than lubricity to make them function smoothly. I think crankshaft, rod bearings and and camshafts bearings and lobes have a higher need for lubricity. If the oil was bad enough to make the tranny act up then the engine would be in trouble. I suspect the cause of hard shifting, if that is what is meant by notchy" could be a dragging clutch.
I have a 99 VFR800 with 124,541 miles on it, the latest 79 put on today. It still runs and shifts as nice as the day I bought it. I have always used Rotella Synthetic.
