My 1999 E300 Turbo diesel is

1. My second MB

2. My first diesel

3. My first turbo vehicle

The question: I have heard that one should let the car idle for a minute or two to let the turbo cool down. I have also heard that the turbo spins at about 100,000 RPM. Are these statements accurate? Should cool down be done everey time it is driven and what are the implications of not allowing the turbo to cool down?

Not really a concern, in my opinion. The warnings to cool down the turbo really only apply to older gasoline engines. The turbos in those engines ran at high enough temperatures that a quick shutdown - which stops the flow of oil which cool & lubricates the bearings - could "coke" the oil. Essentially, the oil got cooked - it was overheated.

This is very unlikely to happen in your diesel. The temperature of exhaust gasses in a diesel engine is much lower than in a gasoline engine. Hence it is difficult to get the turbo hot enough to cause such a problem. Perhaps if you are driving the tar out of the car and then immediately pull over and shut it down. But just cruising along the freeway or running around town - no cooldown needed. By the time you pull into a parking spot, that's all the cooldown it needs.

One thing you can and should do to insure a long turbo life is use a synthetic motor oil. Mercedes is requiring such for the extended oil drain intervals on this car anyways.

Thanks for the prompt reply. The level of technical prowness in this forum always impresses me. The car has synthetic oil in it now and it will always have it. I am currently 'setting up' to do my own oil change with a topsider because it costs me almost $100 to have the dealer do it. The service dept at my dealer is great but at $5 to $6 a quart and the car taking almost 8 quarts I think I can save some money and change it more often.

Run a good synthetic like Delvac 1 and do not worry about turbo cooldown.

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1995 S-350
370K + SOLD
1952 220B Cabriolet
39K kilometers + SOLD
1998 E300D
310K +
2012 E350 BlueTec
120K