Coking of engine oil in the om642?

gawdzinner

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I did some reading in a diesel magazine and it said to let the exhaust temperature cool to 400 degrees fahrenheit or risk having the engine oil "coke" in your turbo.

I have already got into the habit of letting the exhaust temperature drop to 500 degrees by idling after parking, but to drop to 400 would take quite a bit more idling.

I used the Mobil 1 ESP 5w-40 (229.51 rating), do you guys think I should be worried about coking?
 

WG M-B

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As far as we have encountered so far the coking issue only happens on dpf equiped cars. Best to have the dpf mapped out/ give it a damned good flushing then run in on proper diesel oil.
Problem solved.
 

oigle

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Coking has always been a problem, particularly with petrol engined turbos as they run far hotter than diesel. New oil - synthetic - will not "flash" off under about 350°C but as time goes by and fuel dilutes the oil, the flash point rapidly lowers. Cars used on relatively short runs will suffer from this problem more due to the oil not getting hot enough to evaporate the fuel out of the oil. Extended oil change periods can really create problems here and it would be advisable to idle your motor for a reasonable period after a hot, high boost run, in these circumstances. I am a believer in yearly oil changes for this very reason.
 
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gawdzinner

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thanks guys, I will continue to let it idle until exhaust temps hit 500 Fahrenheit.

I did have a petrol engined turbo back in the early 1990's. The oil return line eventually "coked" up inside and starved the turbo of oil until it failed, which caused a very expensive repair. I'm now really cautious with turbo vehicles.
 

oigle

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thanks guys, I will continue to let it idle until exhaust temps hit 500 Fahrenheit.

I did have a petrol engined turbo back in the early 1990's. The oil return line eventually "coked" up inside and starved the turbo of oil until it failed, which caused a very expensive repair. I'm now really cautious with turbo vehicles.

That should be cool enough, even with some fuel dilution. Better to be sure than sorry....
 

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