View Poll Results: do you let your car idle before shutting off
I always let my car idle before turning off.
264
36.72%
I always let my car idle if I am running it hard before I turn it off
211
29.35%
I just turn mine off when I\'m done.
55
7.65%
Doesn\'t matter, I have a turbo timer!
189
26.29%
Voters: 719. You may not vote on this poll
Poll: Do you let your car idle before shutting off?
Anyone who lets their car idle before turning it off obviously never had an oil temp gauge. When idling, oil temperature RISES, the complete opposite of letting your car cool off. This is why turbo timers are a waste of money and do not help.
The best bet is to drive soft your last mile or so before you turn the car off... if you are at the drag strip, drive slowly in the return lane to cool the car down...
This is why race teams have cool down laps... the don't have "lets park for 30 seconds and let our car cool down" laps
I've had 6 turbo cars, and the turbo never went bad on either of them, and my 90 GST had 189K miles. I NEVER let it idle before I turned it off...
The best bet is to drive soft your last mile or so before you turn the car off... if you are at the drag strip, drive slowly in the return lane to cool the car down...
This is why race teams have cool down laps... the don't have "lets park for 30 seconds and let our car cool down" laps
I've had 6 turbo cars, and the turbo never went bad on either of them, and my 90 GST had 189K miles. I NEVER let it idle before I turned it off...
This may have been posted before... i just didn't wanna read all 8 pages.
to get an idea of how long to cool your car down... when it's dark out, and the car fully warmed up, go out and drive in boost for a few minutes. find a place with no overhead lights and it's dark. park the car(start counting), and get out and pop your hood. you'll see the turbo glowing red and getting dimmer as your egts drop. keep counting till it stops glowing. if you have an egt, watch for your temps to get back to normal idle condtions. this should be more like a few minutes...
yes your oil will heat up initially, that's because the oil is moving slower through the turbo, it will cool down when the turbo cools down....and just think, that temp increase, is over the entire oiling system...think of how hot that oil gets actually inside the turbo...
with synthetic oils these days, you technically "don't" need to let your car cool down because todays oils don't breakdown like older organic based oils...another reason mobil1 synthetic is factory fill...and mitsu didn't put a TT on it from the factory either....but....
the majority of us paid 25-30k for their car....is it worth spending an extra dime or two in gas and a few min here and there to protect your baby... whatever the magic time to cool it, or magic oil that won't break down...it's common sense to not let oil just sit inside a 1000+ deg turbo...when its running, it's flowing, and everything is cooling.
I hope this helps someone.
to get an idea of how long to cool your car down... when it's dark out, and the car fully warmed up, go out and drive in boost for a few minutes. find a place with no overhead lights and it's dark. park the car(start counting), and get out and pop your hood. you'll see the turbo glowing red and getting dimmer as your egts drop. keep counting till it stops glowing. if you have an egt, watch for your temps to get back to normal idle condtions. this should be more like a few minutes...
yes your oil will heat up initially, that's because the oil is moving slower through the turbo, it will cool down when the turbo cools down....and just think, that temp increase, is over the entire oiling system...think of how hot that oil gets actually inside the turbo...
with synthetic oils these days, you technically "don't" need to let your car cool down because todays oils don't breakdown like older organic based oils...another reason mobil1 synthetic is factory fill...and mitsu didn't put a TT on it from the factory either....but....
the majority of us paid 25-30k for their car....is it worth spending an extra dime or two in gas and a few min here and there to protect your baby... whatever the magic time to cool it, or magic oil that won't break down...it's common sense to not let oil just sit inside a 1000+ deg turbo...when its running, it's flowing, and everything is cooling.
I hope this helps someone.
While driving, air is hitting the oil cooler and should give you cooler oil temps. But your EGTs are also higher when you're driving.
When you shut off your engine, oil and coolant stop circulating and the heat from your exhaust (turbine housing) will transfer into the turbo's center cartridge. If the temperatures in the center cartridge get hot enough, the oil will boil and char or coke up. Build up of that char will lead to premature bearing failure as it starts restricting oil flow through the turbo.
This used to be an issue many years ago with older conventional oils. Good synthetic oils, such as Mobil 1, have a much higher boiling point compared to conventional oil. So I wouldn't worry too much about oil charring up if you let the car idle until EGTs settle down before shutting off.
I normally just let my car idle for 30-45 seconds after a long highway drive or hard run and just shut the car off if I'm city driving.
When you shut off your engine, oil and coolant stop circulating and the heat from your exhaust (turbine housing) will transfer into the turbo's center cartridge. If the temperatures in the center cartridge get hot enough, the oil will boil and char or coke up. Build up of that char will lead to premature bearing failure as it starts restricting oil flow through the turbo.
This used to be an issue many years ago with older conventional oils. Good synthetic oils, such as Mobil 1, have a much higher boiling point compared to conventional oil. So I wouldn't worry too much about oil charring up if you let the car idle until EGTs settle down before shutting off.
I normally just let my car idle for 30-45 seconds after a long highway drive or hard run and just shut the car off if I'm city driving.
Evolved Member
Joined: Jun 2003
Posts: 1,118
Likes: 0
From: Riverview, FL
Either let it idle for about a minute before shutting it off, or just drive slow and easy (no boost) the last mile or so before your destination...that will be enough, especially with synthetic oil. 
Turbo timer set for 30 sec here 60 secs if I drive it hard for longer than an hr.
Although with todays synthetic oils, its not completely necessary to use a turbo timer... Although, That is comment based on opinion and past experience.
60 secs if I drive it hard for longer than an hr.Although with todays synthetic oils, its not completely necessary to use a turbo timer... Although, That is comment based on opinion and past experience.
