Automotive: pre-oil-change engine cleaners: asking for trouble?

I recently bought a very nice “pre-owned” car (got it for a song), during which time the female owner sheepishly admitted to having been less than diligent about her oil changes. The price was so amazing that I got the car anyway. Her last oil change? 20,000 miles ago! (Odometer reading 63,000)

Scanning the auto section at WalMart recently, I noticed cans of engine cleaner that you can use just before an oil change. The idea is that the cleaner will loosen deposits and leave you with a squeaky clean engine, more or less.

Isn’t dislodging engine gunk and grime a Very Bad Idea?

Please clue me in. (Facts are welcome.)

Hard to say. What’s it called?

It’s probably a thinning and wetting agent, you put it in, run for a few miles, then change the oil and the oil filter. Might be worth a try.

If the car’s run that long without a change, I’d consider doing the next change, and another filter change as well, early.

Some additives are kerosene, which is traditionally used to clean engine parts, and kerosene is used clean boat motors after getting submerged and other uses.

It’s debatable - of course. I’d change the oil, which gets new oil and new detergents in right away, and I’d probably go only 1500 miles on the new oil and get back to my 5k oil changes (or whatever depending on use/insturction manual)

What kind of car is it? Make, model & year.

Is the engine a bit old? Like, 10 years or more?

If you dont have any oil leaks now, you will after you use the motor oil flush.

The “crud”, carbon deposits and varnishes, often plug up gaps in mating surfaces, like seals and gaskets.

If its a newer engine, like 5 years or less, you’re probably safe.

It’s risky. It’s not a standard repair procedure, and for good reason. If it loosens deposits, and some of those deposits get stuck in a critical oil passage, it could cause some major engine damage in short order.

The lack of proper maintenance has surely shortened the engine’s life, and it’s not impossible that it could suffer a major failure soon anyway. Still, I think it’s questionable that this product would make it better. If it were mine, I wouldn’t take the chance of making it worse.

1992 Corvette. Waaay under blue book. It sat in a garage for several years, unused, then she finally drove it some just because. Belonged to her late husband. Sad memories.


Well, you might need to put the money you saved into some serious work :smiley:

The engine flush stuff will probabaly cause some leakage depending on the seals conditions. Is there any leaks now? Can you get under the vehicle? Do you know if any major repairs were done?

I’d probably do what Philster said, do 2 oil changes within 2K miles and check the condition of the oil. Also, log and/or check your oil continuously for the next several weeks.

Can you get to the spark plugs? Pulling one and checking it out might tell you some things.

In my experience, these engine flush products do more harm than good…many of them are just kerosene, with some other solvents mixed in. As far as the crud…most modern oils do not make sludge like the old-time non-detergent oil. I would follow the earlier advice, and get several oil changes within the next 5000 miles. Watch your engine temp gauge3 like a hawk! If the car shows any signs of overheating, get it to a mechanic right away-you may have a blocked oil passage. You might also pay a mechanic to drop the oil pan (not an easy job on a 1992 Corvette-I believe that a crossmember must be removed), and clean the sump out (and change the oil screen.)
Most likely, you will be OK-and don’t ever use a product called “B@rd@ahl”-it can indeep cause you problems.

You know, there’s actually a chance that no harm at all was done by not changing the oil.
Particularly with synthetic, the oil could have survived 20,000 miles without breaking down substantially. At that point your real problem would be possible contamination of the oil.
If you’re so inclined, you might want to find a company that does oil analysis and send a sample of the oil in your 'Vette off to them. If they say the oil is not contaminated beyond tolerance and has not broken down chemically, that could allow you breathe a little easier.