1999 Chevrolet Truck

Engine Mechanical problem
1999 Chevy Truck V8 Four Wheel Drive Automatic 140000 miles

This has a 350 engine with the stock oil cooler in the radiator. I rebuilt the engine recently. When I first filled it with oil it took seven quarts. When I gave it the first oil change after 500 miles, only 5 1/2 quarts drained out. I imagine the other 1 1/2 quarts are in the oil cooler. I have two friends with similar trucks, and they say when they change oil it only takes 5 1/2 quarts too. How do I drain the oil from the oil cooler. Is everybody leaving 1 1/2 quarts of dirty oil in their trucks every oil change, or am I just crazy?
February 5, 2009.

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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That, s amazing. Nobody else has ever been able to tell me this. Everybody out there with a truck like this should be mad as hell that this is not common knowledge. Every time that they have had their oil changed, whoever did it left 1 1/2 quarts of dirty oil in their engine. I have not heard of this, and I have been looking in forums like this for awhile now trying to address this problem. It is not in any manual that I have ever seen.

Feb 6, 2009.
Yeah, it's pretty weird. I guess is because not all vehicle is equipped with the oil cooler and maybe other people just don't notice.