wwest

Sorry, it's the 1% times I have the most concern about. My '01 F/awd RX300 runs on nice and quite, comfortably riding, summer use only BridgeStone Turanzas throughout the year. One set of tire chains are ALWAYS on board for the REAR, and a second set in the wintertime to add on the front. I NEVER hesitate to install tire chains when and if needed.

I'm surprised that you class the Sienna as AWD. The Sienna has an optional F/awd system that is there ONLY for marketing purposes. With three fully open diff'ls, front , center, and rear, it is only, really, a ONE WHEEL drive system. Public outcry has now resulted in the availability of a PB control to disable TC, your Sienna's (and Highlander, AND RX330/350) ONLY backup for the ONE WHEEL drive system. What does that tell you...??

That's the danger of FWD, engine torque to the VERY same wheels you rely on for stearage is NEVER a good idea. Ask an experienced owner/driver of a RWD/4WD vehicle how they drive on the slippery stuff and they will tell you RWD. Like 4WD, F/awd is virtually PERFECT for getting you up and going initally, but once underway at a decent road speed, >18MPH, any 4WD owner having been around for awhile will tell you to shift into RWD. You can't do that in your FWD, or even your F/awd, so OFF the road you go. Or you could practice quickly shifting your transaxle into neutral (as recommended by the AAA) in the event you find you need to dedicate your front wheel traction totally to directional control, NOT engine leading or lagging torque. Your F/awd Ford Edge WILL NOT help you stay out of that ditch, only a RWD or R/awd system can help you with that problem. Unless you remove one front halfshaft and apply a constant 12 volts to the rear driveline clutch, that is.

"..I'm puzzled..." Don't be. The general public is just now waking up, or being woke up, to the patently UNSAFE nature of FWD. The industry is responding to this "threat" by offering a veritable myriad of F/awd systems many of which are mostly non-functional and there for marketing purposes only. Give me a simple RWD instead of ANY F/awd system any day of the week or time of the year. The Honda/Acura SH-AWD system is the only F/awd system acceptable to me but I don't care for the B747 cockpit nature of the RDX.

I have read somewhere that the Edge's 6F transaxle has a variable displacement ATF oil pump so that fluid doesn't have to be bypassed at high engine RPM but will still supply enough pressure/flow with the engine at idle. Does anyone know how this was done, which technique? Obviously this would increase the overall transaxle efficiency somewhat but I suspect that its real purpose is to overcome the throttle lag programmed into the DBW, e-throttle, system in earlier FWD vehicles. The 1-2 second delay was to give the transaxle clutches more time to fully seat with the engine at idle and thereby very little ATF pressure. Comments?