Hi,

Question about the 2 minute cool down for our 996 Turbos.
I use my car as a daily driver for really short drives. My office is less than 4 miles away from my home and the engine is hardly warmed up when I arrive either direction. Needless to say that I don't 'get on' the car beyond 3,000 rpm for such short rides, but what about the 2 minute cool down rule ? I've been respecting it religiously - but start to feel like I'm losing a lot of time. Do I need to go through the 2 minute cool down in case I didn't spool the turbos on a short ride ?

Thanks for your help !

By the way - I do do take the car for spirited rides during the weekend and will make sure to change the oil each year (i.e. every 5,000 miles)

 

the "2 minute" cool down is to help eliminate "coking" of the turbo which is the oil baking on the inside of the center section. it's guestimated that 2 minutes of moving "cooled" oil throught the turbo helps this. If you're not driving the car such that the turbo isn't being cranked at least some of the time, IMO, I wouldn't worry about it.

 

For my understanding let the engine go in idle wait a second or two and thats enough if you drive like you write

After a fast trip with glowing turbos and boost, 2 min not enough, drive the last miles slow without boost this is better than a idle cool down

 

do you get blue smoke on start up with such short trips?

 

Right. After a spirited drive, I take it easy when I get within a mile or two of my house, plus I have a 1000' driveway. By the time I get in my garage, I figure I'm good.

 

Good question.
I've had it maybe 5 times in 7 months of ownership. Fist time it happened, it scared the Bejeezes out of me.
Last time it happened, the car had been through it's normal cool down, so I'm not sure there's a 100% positive correlation.
The smoke was not blue though, more like grey/white....

 

that is normal too...

 

I publicly stick to 2min....if I drive it hard or at least get it warm.

If I am say at a place where 3 digit speed is legal and there is a pca instructor next to me...might be a lap or two cool and 2 minutes at idle (the lap is for the rotors and pads). For your sort of stuff..1 minute is my unofficial rule... So much for rules.

Such short drives are really tough on cars...you should get a beater....

I wish Porsche put a cool down timer in the car. Our xc70 by Volvo(wagon) just runs a pump on shut off..water cooling I think though...... You would think on a 150k car they could have done the same. (probably would be pentosin driven with a separate line system, valves the make noise, and reservoir though). But, it adds weight and there would be threads about taking it out of the car if you just run it 2 minutes to save 40 pounds....

 

Another thing, if you are not driving the car at least 10-12 minutes, then it isn't heating up enough to evaporate all the moisture from everywhere. If you do really short trips all the time that will lead to problems.

 

interesting

 

You are probably getting a lot of fuel shear/dilution... When cold the engine runs rich- this will cause more fuel to get into the oil (off the rings/pistons)... usually the fuel then burns off after 20+ minutes of driving at temperature.

Fuel will thin the oil and reduce protection. It would be interesting to see your oil analysis at change time....

A

PS Simple solution: Move further away!

 

In order for my to get into my garage and park the car properly,I need at least 3minutes...So I ve got a safety point here However it is better for the turbos to cool down with normal driving(without boosting) than to idle...

 

With all the short drives each week you should probably consider changing your oil more fequently than 1 yr/5000 miles.

 

My .02...From what I have been told by a reputable turbo "manufacturer"...driving slow for a couple of minutes at the end of a spirited ride is NOT sufficient. You need an idle cool down. Now there is debate on exactly how long this is. I was told at least 60 seconds and no more than 120 seconds (heat soak)...REGARDLESS of the length of drive.

see this thread for more info.

 

test your car, drive tonight till the turbos glowing....Then look under your car an wait till the red ligt goes away.....i do this after long high speed trips....in 4 min no turbo goes down from 1000 Celsius to 100...

Then try another ...drive till the turbos do his red ligth and then drive a few miles without boost.....the air cools it down during drive most quicker and more efficient than idle

I drive turbos since 25 years, no turbo with this rules is going under...in many cars..

and your neighbours says thank you.......4 min idle coudl make a little problem with a porsche aftermarket muffler

this is only what i think about this rules, you can do it like you think it the best