Is it bad for our car to sit idling till full operating temp?
As opposed to idling for a minute, and then driving
gently till it's at full operating temp?
thanks,
Joe

 

In fact, is it bad to idle indefinitely?

 

The owners manual says you should start driving the car immediately after starting the car cold but not past something like 4500 RPM, so the car can heat up and the oil circulating asap. After the car is at operating temp it should be okay to idle because the oil then is circulating through out the entire engine.

 

i always let the car warm up for a few mins first... get oil temps up etc...

 

Let the car idle for about 30 seconds, and start driving, keeping the RPMs and load low til reaching operation temps...

 

That brings up a similar question for me. After you've been driving on the highway for a couple of hours, do you actually need to sit there and let the car idle for a couple of minutes before turning it off?

 

Chumpalump, this was discussed in another thread, and
the answer is yes. The exhaust temps need to be as low
as you can to let the turbos cool and let the oild circulate
through them. Even the most gentle driving will put a lot
more heat into the turbos.
Joe

 

Joe,

This is a good question. Porsche's manual says to start and drive. It sounds to me like they are trying to sell motors. I have temp gauges for water, heads, oil and exhausts.

The oil we use is designed to work at a mininum of 158 degrees. Using the car in 70 degree ambient temperatures, if I idle it to 158 degree water temperature, the oil is only approx. 75 degrees. It takes about twelve miles, under 2000 rpm's (this is after idling to bring the water to 158 degrees or the oil to approx. 75 degrees) to bring the oil up to 158 degrees. I might add my water comes to temperature faster than stock 996tt's because a use a product in the water that brings up the temperatures alot faster.

It appears to me that starting and driving prematurely wears the motor.

 

But this theory brings up another question: How many engine malfunctions did people experience with the turbo engine? To me it seems that the TT engine and the GT3/GT2 engines (M96.7X) is highly reliable, while the standard Carrera engine (e.g. M96.0X) is really not. I had a major engine malfunction in a 996 C2 myself a couple of years back... but I never heard people having problems with the TT engine. Did you hear anything different? Who has experienced engine problems with his TT?

 

Let the car warm up then drive off. The idle rule in the manual is strictly for reducing environmental emissions...

 

Let idle for 30 seconds then drive for 5 minutes under no boost. You let idle too long and you will create condensation. The system will be fine if you follow those rules.

 

I'm certainly no expert, but I've always understood that these idle after startup recommendations are made because of the lack of efficiency of catalytic converters at low temperatures and relatively high emissions prior to the cats warming up, not because the engine oil needs to heat up to lower its viscosity and reduce frictional wear inside the engine.

 

Listen to Porsche engineers or a bunch of internet dudes who think they know better?

Just start and drive. Keep the revs low until the engine oil, tranny oil, diff oil... everything warms up. I imagine it's safe to go full throttle after a good 10-minutes of easy driving.

 

Wouldn't it be a bright idea just to get a turbo timer for when your done driving in order to let the turbos spool down?

 

The system will allow the cats to heat up within the first 2-3 minutes of startup. There is a procedure the system goes through to promote cat preheat.

It is as much as an issue with the oil as it is anything.

My experience comes for years of building Porsche motors, not just hearsay