Coking' of the Engine Oil

[ATM]

“Coking' of the Engine Oil – The critical point affecting both the oil and the turbocharger arrives when the engine is shut off after the turbocharger has been under rigorous use for some period of engine operation. At this point, the oil no longer circulates through the shaft bearings to carry away the heat.”


Is oil coking still a concern for our cars or has the technology gotten better to where simply turning off the car after spirited driving is fine?
Do you guys Let the car run idle for a few minutes before engine Shut down?

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[JT Si]

Water cooled turbos like most modern turbos (and ours) are designed to exploit an effect called thermal siphoning. In addition, a water cooled turbos operating temperature is significantly cooler than an oil only turbo.

Basically the turbo is cooler, and the heat that is remaining causes coolant to siphon through it after engine shutdown, continuing to provide a cooling effect.

No need to idle before shutdown - unless you just finished a hot lap or a drag race. But a leisurely driving cool down is far more effective than idling in that case.

 

[charleswrivers]

“Coking' of the Engine Oil – The critical point affecting both the oil and the turbocharger arrives when the engine is shut off after the turbocharger has been under rigorous use for some period of engine operation. At this point, the oil no longer circulates through the shaft bearings to carry away the heat.”


Is oil coking still a concern for our cars or has the technology gotten better to where simply turning off the car after spirited driving is fine?
Do you guys Let the car run idle for a few minutes before engine Shut down?

It is not an issue and hasn’t been for decades... hence why turbo times aren’t marketed anymore. Virtually all OEM and most aftermarket turbochargers are water cooled and will have a natural circulation flow without the need for the water pump operating to cause water to move through the turbo to cool it sufficiently to prevent oil from coking. When looking at old 300zxs... it’s what the ‘85 had over the ‘84 on the Z31s. The design change for Garrett is that old.

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