What do you all think of this statement by Subaru? This came out of the End Wrench, Fall 2002, Number 20. Does this really mean I don't need a turbo timer anymore?
it is not necessary to perform a cool down / idling period procedure on Subaru WRX turbo models, as was recommended with past turbo models. The current 2.0 liter turbo engine has a far greater cooling capacity and, coupled with technology advances, makes this practice no longer necessary. This explains why information about a cool down is nor included in the Impreza Owner's Manual.
The heat contained in the turbocharger begins to vaporize the coolant at the turbocharger after the engine is stopped. This hot vapor then enters the coolant resevoir tank, which is the highest point of the cooling system. At the same time the vapor exits the turbocharger, coolant supplied from the right bank cylinder head flows into the turbo. This action reduces the turbocharger temperature. This process will continue until the vaporizing action in the turbocharger has stopped or cooled down.