Talking about turbocharged engines, of course. It used to be common knowledge, especially in the trucking industry, that you let the engine idle for about 5 minutes before shut down so oil wouldn't bake and coke up in the turbo bearings. With modern oils, especially the synthetic options we have now, is this still necessary? As I understand it, a lot of newer turbos are liquid cooled as well. I usually let the engine idle for about a minute before shutdown on my 7.3 Powerstroke after a highway run, and about 5 minutes if it's been towing. Am I wasting my time? Or is this still a good thing to keep doing?