Which is more efficient at power and torque transfer--MTs or ATs? (Best Motoring - AT Transmission Techniques) Since the torque converter turbine wheels don't touch each other, ATs don't transmit torque directly, resulting in transmission efficiency 95% of that of MTs. (In other words, MTs are more efficient.)

So transmission fluid runs through the torque converter and transmission? Yes.  This is why AT cars have so much transmission fluid when compared to MT cars. That fluid must be in good shape. The transmission fluid and filter should be replaced regularly.

What else does transmission fluid flow through? DSM ATs have transmission fluid coolers. That's that cooler on the left side of the car that many people mistake as an oil cooler. (AT people, check it!) The temperature of the tranny fluid in these cars rise high, so tranny fluid travels through the AT fluid cooler and the radiator.

AT transmission stall speed--what is it? It's the maximum speed the engine will go (RPMs) without the transmission engaging. Stall speed is reached when the accelerator is pressed, but the brake is also held down. The car won't go because the torque converter doesn't allow the tranny to engage. Stall speed for DSM ATs is between 2500 - 3000 RPMs. Changes in stall speed can be incorporated with engine timing. You can change the stall speed of the torque converter by changing the pitch of the turbine wheels inside the torque converter through which the transmission fluid flows. 

Transmission fluid--what kind is good? For everyday driving, synthetic, non-race transmission fluid is best (??? Eh? I thought race stuff was generally better???)  Like motor oil, synthetic transmission fluid does a better job of handling heat and preserving engine internals through chemicals and less friction of parts. (Also found out that Mobile 1 synthetic isn't full synthetic???!??!  Blew me away. I always buy the stuff by the case...For more on motor oil, check out the engine oil bible at:
http://geocities.datacellar.net/MotorCity/2195/engineoil_bible.html )

Racing ATF isn't as good for your trans because it is thinner to allow increased fluid flow and thus faster shifting. Thinner fluid provides less frictional protection thus increasing wear. Some of these formulaes have no/ less frictional modifyers which also contributes to wear. AutoMotion said look into synthetic transmission fluid like Amsoil and Red Line. Synthetic is more expensive, but better for the transmission in the long run.

What about crap products like Dura-Lube, Slick 50 and Prolong? There not crap.  (??? No? I thought so. I thought that stuff was false advertisement.) Fluid additives bond to parts and prolong the life of engine and transmission internals. But be careful. Some products like Slick 50 uses Teflon. Slick 50 goes in as a liquid, but when heated, the Teflon in the fluid turns solid. When heated over a period of time, these solid particles can do more harm than good. Should stay away from them, tho.

Shifting gears a bit to gear ratios... (thanks Todd)
Manual FWD:  1st 3.090, 2nd 1.833, 3rd 1.217, 4th 0.888, 5th  0.741  Final 4.153
Manual AWD:  1st 3.083, 2nd 1.684, 3rd 1.115, 4th 0.833, 5th 0.666
Reduction ratio primary: 1.275  Reduction ratio front differential: 3.800
Reduction ratio transfer case: 1.074

Auto FWD:  1st 2.55, 2nd 1.488, 3rd 1.000, 4th 0.685  Final 4.376
Auto AWD:  1st 2.55, 2nd 1.488, 3rd 1.000, 4th 0.685  Final 4.361

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