Are engine flushes necessary?

Dear Car Talk

Dear Car Talk | Jul 01, 2004

Dear Tom and Ray:

I have a question about engine flushing. The other day, I went to my usual mechanic for my 3,000-mile oil change and tire rotation, and he tried to sell me on a "Bilstein Engine Flush." He showed me a vial of sludgy black liquid, presumably from some poor schnook's fouled engine, and another vial of clear, amber fluid, presumably the "after" effect. My question is, of course, is it worth it to get this flush, or am I just wasting $60? -- Terence

RAY: I hope he didn't steal those sample containers from his doctor's office, Terence. Or swap them by accident. Can you imagine some poor guy right now, sitting across from his doctor, getting the bad news that he has a blown head gasket?

TOM: Actually, Terence, we've found that the number of mechanics who recommend engine flushes is directly proportional to the number who are making payments on an engine-flushing machine.

RAY: It's certainly not going to hurt your engine, Terence. But in the absence of any evidence that your engine is full of crud, I'm not sure it's really necessary.

TOM: An engine flush is a machine that removes your oil and runs a heated solvent through the all of the places where the oil flows before adding back new oil. Supposedly, it removes any gunked-up oil and varnish that are clogging up your oil passages. Bilstein is the reputable company -- best known for its shock absorbers -- that makes this machine.

RAY: I have no doubt that it works. But if you've been changing your oil every 3,000 miles -- or even every 7,500 miles -- you really shouldn't have any gunked-up oil in there in the first place.

TOM: If your brain had been taken over by space aliens and you had "forgotten" to change your oil for the past 30,000 miles, then I think a complete engine flush would be in order. But I just don't know if doing it as "preventive maintenance" is really necessary.

RAY: It's necessary for the guy who bought the machine and needs to make his money back. But I'd say it's overkill for most people, Terence.

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