That is correct. About 10% of the engine oil is still left in the cooler. Theoretically, the dirt should all be in the filter. The small amount of dirty "looking" oil left in the cooler should not have any contaminents in it that could damage your engine. However, I don't really believe this is true and I suggest flushing the cooler every oil change. It will cost a little extra but it is worth it in the long run. To flush the cooler, do the following.
Drain the old oil then pour in a couple of pints of new oil and turn engine over a few times (dont start it). Replace old oil filter after flushing cooler then fill with new oil.
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Friday, February 6th, 2009 AT 2:07 AM