As has been mentioned, a lot of this is discretionary, regardless of whether it's warranted. There is a huge difference between prudence and wastefulness (though the line is narrow and vague). Most of the cool-down procedures I hear/read about aren't nearly as bad for the car/environment/etc. as warm-up procedures in the winter. In comparison, a shorter period of cool-down could be considered inconsequential.
Originally Posted By: rooflessVW
After FULL LOAD operation, not normal operation. Are you normally at full chat right before you park?
The manual also says that excessive idling is no bueno. Idling around town and then idling for 5 minutes is just redundant and wasteful.
Originally Posted By: 4WD
Fortunately most of us don’t live on an interstate exit ramp … so a couple side streets going home, or searching for a parking place in town … should deal with this without any waste …
Bingo! Most of us don't rally-cross through our neighborhoods, and then Tokyo-Drift sideways into our driveway, with the turbo at full red metal!
Even those who live directly off of the highway or at the top of a (low-grade) hill (I'm not talking about a mountain pass here) are typically driving at VERY LOW LOAD just prior stopping the vehicle.
Specifically, I've logged requested torque and calculated load for my previous turbo Subie while on the highway, even at high speeds, and the numbers are low; I would not consider any additional cool-down required, though engine-braking through the off-ramp and a small bit of low-load driving to my destination should cover even the fraidiest of cats.
I've checked logs after climbing up a steep grade to the Gunks in NY and the numbers weren't nearly as high as making a WOT run to redline in 3rd gear. At 3.5-4k RPM, my engine is making sufficient power without having to use more than a trivial amount of boost. With that said, it was often fun to boost WOT out of some of the corners and reach redline before engine-braking through the next switch-back on our way up. The time it took to pull into the trail head, pay for a pass and find a parking spot (as little as a minute or two) is all that I felt was necessary for cool-down after a more-aggressive climb. I wouldn't cool-down at all if I'd climbed the hill more sedately.
Originally Posted By: Hammehead
My garage is at the end of a steep uphill, so I give 30 seconds for my NA cars to let the hot ring pack shove heat to piston skirts and the liners and then not heat stressing the small quantity of oil between the piston rings and its channel, below piston crown and wrist pins.
What RPM is the engine at for the hill? How long is the hill?
Even 4-5k RPM, especially if the hill is only a short distance, is nothing. Feel free to do as you please with your vehicle, but I doubt any specific cool-down is warranted. If your engine is poorly designed and the oil spray flow to the crown et al. is poorly designed, then I rescind my argument.
Originally Posted By: Hammehead
How could you know? You´re using Edge 0w40 in there ... There´s scientific study (Jaguar) that we, real Bitogers know, showing that a high rpm wide open throttle, the piston crowns, and top rings go up to 470-490F, and the oil won´t like that after several cycles of heat soak.
You're driving WOT directly into your driveway? Was your engine oil temp at peak value just prior to entering the hill? I'm asking sincerely, not sarcastically. You very well could live right at the end of a very long, very steep grade, for which even I would consider your cool-down regiment prudent. If not as extreme as I'm imagining, then I'd say it's not necessary.
