Rinsing out an engine with a quart of oil?

Dear Car Talk

Dear Car Talk | Nov 01, 1993

Dear Tom and Ray:

A friend of mine suggested that when changing my oil, I drain out the old oil, and add just one quart. Then run the engine for a few minutes to kind of "rinse it out." What are your thoughts?

RAY: I'll bet this guy received a special commendation from the Engine Rebuilders Association at their last awards banquet. This guy is nuts, Tom.

TOM: The idea of "rinsing out" the engine is a good one. But running the engine on one quart of oil is a very bad idea. You'll do a lot of damage, even if you only do it for a few minutes.

RAY: It would be like draining all the blood out of a patient during a transfusion, and then asking him to walk around for day or two with just a couple of pints in his system, in order to "rinse out" his veins and arteries.

TOM: The truth is, when you change the oil, you ARE rinsing out the engine. One thing the oil does is collect all the contaminants, and carry them out of the engine when the oil is drained. So if you change your oil regularly (we recommend every 5,000 miles), and you change it while the engine is warm (when the oil is holding more contaminants in suspension), there's no need to do any additional "rinsing."

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