Warm Down Procedure - Smoking or Non-Smoking

[Homeboy981]

We all know, or should, how to properly warm up our vehicles. My concern is when we are done, and parking it in the garage. What is the WARM DOWN PROCEDURE?

Maybe some of you older members can chime in. Talking it over with the North Texas Boxster founder and he said I should ask…

We have experienced similar observations in that if you let the Boxster "idle down" for a minute or more, same as with a turbo-charged vehicle-not ours, you get smoke when you start up. However, when you let it "idle down" for less than 15 seconds and just turn it off, you do not get smoke.

So SMOKING or NON-SMOKING?
What is the proper WARM DOWN PROCEDURE FOR A BOXSTER?
How long should you let it idle?

We are trying to accomplish two things:
1). Warm down vehicle enough to provide as much oil on next startup as possible and/or least amount of wear, and;
2). Does not cause it to smoke upon next startup. Unless we find out, in this case, smoking is good. i know they are supposed to smoke a little….but should we encourage it?

Your opinion is welcome.

[san rensho]

On the track, shutting down the car immediately after a run will cause it to smoke at next startup, but if you let it idle for a few minutes, no smoke. Also helps cool off the motor.

So, if you ride the car hard and put it to bed wet, it will smoke.

[BYprodriver]

If you drive a Boxster hard (high rpm & hard cornering) right before you turn the engine off, the 2 oil scavenge pumps may not have time to minimize the amount of oil left in the heads instead of being pumped back to the "integrated" oil sump. If you park on a unlevel surface this can make the problem worse. The longer the car sits in this state the more drops of oil can drain into a cylinder. Enough oil in the sump to safely start the engine will never be a issue unless the car is parked on a steep grade. (45% or more) So just do a cool down lap before coming in, park as level as possible, & let engine idle long enough to stabilize oil & coolant levels.

[Overdrive]

My car hasn't been doing much smoking lately, and I've yet to notice any smoke on startups at the three autocrosses I've been to so far. I have never shut the car off right after running the course, though. Nevermind that it's been considerably hot the last two events, but I run the A/C after running the course to force the radiator fans to kick in, and let the car idle for maybe 5 minutes before killing the A/C, then give it another minute to let it shut the fans down, and wait out the intake fan on the right if it happens to be on.

Where I've parked the last few times is a slightly forward sloped section, so my unlevel state can't be helped, and I'll admit that I'm not actively looking for smoke on my startups, but if I'm not outside of the car I'm usually already strapped in and backing out of the spot, so I'd notice if I had any startup smoke through the back window.

[shadrach74]

Idling a normally aspirated car as a cool down procedure is sub optimal in my book. Drive it gently for the last 5 to 10 minutes and then shut it down. Idling in the garage before you put the door down has little utility. I feel the same about turbos, but I've never instrumented one to see.

[AndyA6]

OK, here's my take FWIW. If you run your car hard, high rpm, high loads, so everything is really really hot it is highly adviseable to drive for a few minutes at approx. 2,500/3,000 rpm with little as possible load to let things cool down.

Back in Germany after hours of full throttle/high speed runs we always drove the last 2 miles to the gas station at a slower speed to get things to normal. Never a problem!

Idle at a standstill does nothing or makes things worse, air movement is needed.

[Overdrive]

Originally Posted by AndyA6

OK, here's my take FWIW. If you run your car hard, high rpm, high loads, so everything is really really hot it is highly adviseable to drive for a few minutes at approx. 2,500/3,000 rpm with little as possible load to let things cool down.

...

Idle at a standstill does nothing or makes things worse, air movement is needed.

I agree with you, Andy. That's certainly much easier to accomplish on a track than in a commuter lot, though. If I could do those same things I do while in motion instead of parked, I would for the very reasons you state. Although, if the fans for the radiators and the engine bay were not up to the task of cooling the car at a standstill, even if it's only accomplishing the bare minimum, I imagine they wouldn't be there in the first place. It's better than nothing, right?

[blue2000s]

The friction and compression of air in a turbocharger generates emmense amounts of heat. Stagnant oil at the temperatures at which a turbos surface can reach will solidify and/or sludge. The next time the car runs, there is less oil flow due to the clogging created by the previous heat cycle. The lack of lubrication increases friction and temperature even further. This is what kills a turbo, manifolds and seals. So the reason it is recommended to let a turbocharged car idle before turning it off is to allow oil and coolant to circulate through the turbo in a state in which it is not producing heat, bringing it's temperature down to a level that makes it safe for the oil to sit in it. It is perfectly safe to turn of a turbocharged car immediately after a low rpm/load run on the highway or down the street. I've seen a turbocharger on a Toyota last over 350,000 miles in a car that was mostly highway driven, the owner drove like a granny so he didn't let it cool down, and he also always used conventional oil.

Likewise, but to a much lesser degree, a high load on a normally aspirated engine increases it's internal temperature. For the same reason, it is good to let an engine that has been under heavy load cool down before shutting it off to avoid oil sludge. But there is absolutely no reason to regularly let a moderately driven car "cool down" before shutting it off. In most cases, it's not cooling down at all.

[AndyA6]

Sooo, what are we talking about? I guess a cool down is only needed if the engine is really hot like after track use or such.
Here in Utah we have some situations with stop/go traffic in 104F wheather, not good and the engine will be superhot. So on my way home I drive the last mile or so with med rpm and little load, does wonders for cooling down.

And yes, once I parked the car in the garage after a "hot run" w/o cooling down and guess what, blue smoke on start up the next day.

Later,
Andy

[blue2000s]

I wouldn't bother letting a car that sits in traffic "cool down". I have it in quotes because the car has already been idling, more idling isn't going to cool anything down.