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Old 03-10-2019, 02:30 PM
edycol edycol is offline
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Location: Colorado Springs
Join Date: Jul 2015
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Mein Auto: 328i xDrive 6MT
Originally Posted by robnitro View Post
Without dpf, there is no regen which makes the turbo run very hot even at idle/low rpm.

Shutting down during a regen is something that I feel is very bad for the oil in the turbos.
Edycol said that the synthetic oil can handle those temperatures, but it does add to possible coking when the oil is already getting compromised with soot and or depleted TBN.
Without flow on shut down the little oil that remains gets heat soaked.

American diesel is ULSD, and TBN retention is much better than prior to 2009 (which allowed BMW and others to bring these diesels to the US).
Oil that has TBN below 1 is done. It will start to oxidase regardless of whether you shutdown engine during regeneration or not.
That is why 10k OCI should be absolute maximum and 5-7.5k preferred OCI.

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