This is probably a very obvious question for a lot of you, but I was just wondering, why is the cooldown of turbo(s) after a long drive so important, and from what I heard, turbos that are built after 2000+ don’t really need the cooldown?
How long should I keep the engine running if the cooldown is necessary?
By the way, I own a '01 Audi A6 2.7T.
The temperatures that are produced inside a turbocharger are high enough to “cook” your motor oil if the engine is shut off right after a hard drive. I seem to recall that 3 or 4 minutes is the minimum amount of time to let the engine idle before shutting it down after a hard run.
Also–whether your Owner’s Manual specifies it or not, I would suggest that you use a full-synthetic oil in that engine. If it does specify synthetic oil, be sure to match the specification that is listed in the manual.
Here’s a product that allows immediate shutdown of a turbo engine, but still lubes the turbo bearings to cool them down.
For the most part you don’t need to cool down a turbo anymore for stock applications. If your car is running more than stock levels of boost or has an aftermarket turbo on it, then a turbo timer is a good idea. It also doesn’t hurt to use a full synthetic motor oil and premium fuel in turbo applications.
can you truly ensure that you won’t EVER shut off the engine immediately after a “hot” shutdown?
when the engine shuts off the oil STOPS circulating immediately. if the turbo is still spinning at a couple thousand RPM’s, it doesn’t take a rocket scientist to figure out what happens next. the turbo eats itself up.
since you (usually) shut off the car, it has been when you are just driving into a driveway, parking lot, or other dead end. (read running slowly)
since the turbo doesn NOT kick in at low speeds, it doesn’t need a “cool down” period.
usually when you run you car, your turbo only “kicks in” when you give it the gas. BUT, if you do run it hard, then shut it off, it can damage the turbo.
First refer to your owners manual if you have it for your car.
The only time a cooldown would be prudent is say you are driving in boost(you’ll know it)/hard and then immediately pull over and stop. An example would be up a mountain pass at 70MPH and then pull over <1 min to enjoy the nice view. Normal driving the time you spend turning into a neighborhood, parking lot, or garage your turbo is getting cooling.
You are correct on 2000+ turbo engines not really requiring cooldown. For example I own two Subaru’s with turbo’s and both are designed to keep cooling the turbo after shutoff by coolant using natural convection designed into the system to keep coolant flowing until temp drops enough. Audi’s have a similar design.