Six tanks with Techron solved high oil consumption at 140K miles

My wife and I own a 2005, currently with 145K miles. At 130K, it began to burn oil, maybe 1 quart per 2K miles. That rapidly deteriorated, to 1 quart of oil per 800 miles, by 142K miles. No leaks. No (e.g.) smoke upon startup, or smoke upon hard acceleration.

Went to the dealer, hoping it might be something simple, such as a bad PCV valve.. What we heard back was "the rings are so carboned up they hardly make contact with the bore, and there is lots of blow-by". Dealer's advice was either a) $5400 for an engine rebuild, or b) start saving for a new car.

I had never heard of rings being carboned up that badly. Carbon? We'd had what I thought was a problem with knock (pre-ignition) around 120K, but the dealer said otherwise. Barring that, this was the first inkling of upper-cylinder carbon issues on this engine.

Before trashing the car, I decided to try whatever seemed reasonable to decarbon the upper cylinder. Lined up my options. Of the options available, dumping Techron concentrate into the gas tank seemed a) cheap, b) had some evidence of effectiveness, and c) was easy. Other options (Seafoam, various oil additives) were either a lot more work, or seemed like a lot more risk.

Understanding that Techron worked slowly, I bought enough for ten tanks. I figured, ten tanks of Techron, and if that didn't do it, I'd throw in the towel.

Six tanks later, I can say, this worked. Over the last 1K miles, oil went from full, to a hair under full. That is, oil consumption ( 5 w 20, did not move to thicker oil) has stopped.

Gas mileage remains at near-new levels. Recent round trip, Washington DC to Richmond, averaged 49 MPG, with a considerable fraction of that at 75 MPH with no drafting.

So, this worked. I don't really understand why it worked. I am just attesting to the fact that it did. I completely realize that the oil control ring is at the bottom of the piston body. I don't really understand why de-carbonizing the upper cylinder could possibly matter that much for oil consumption.

I just want to say that, if you are in this situation, you might consider a few tanks with Techron concentrate, before tossing in the towel on your high-oil-consumption Prius.

In summary:
We went from modest oil consumption (1 quart / 2K miles) to high oil consumption (1 Q/800 miles) in short order. There was no obvious smoking at startup or on hard acceleration. There were no leaks. The dealer said "carboned rings", but offered no further useful advice. We tried consecutive tanks of gas with Techron concentrate added. Not because it was the obvious choice, but mostly because it was easy. And that appears to have resolved the problem.

Obviously, if you're burning oil due to worn rings, bore, or valve guides, this isn't going to help. But in our case, it was due to upper cylinder carbonization. Really, to carbonization of the rings. And Techrnon appears to have fixed that. For us.

 

Let me answer as many of these as I can.

I buy whatever gas is handy. Shell most of the time, I think, as that is closest to my house. I just don't pay attention to it, and I'm sure my wife doesn't either.

Yes, four bottles left. I think maybe I'll do this a couple of times a year from now on.

The Techron product is as pictured above, but it's the smaller bottle. "Techron concentrate plus, complete fuel system cleaner", 12 fluid ounces, for up to 12 gallons of gasoline.

Can I post an Amazon.com link here? Let me try it as plain text:

It says all the right words on it: "Safe for catalytic converters and oxygen sensors. Can be used with ethanol containing fuels and in gasoline/electric hybrid vehicles."

I looked at the last bottle of oil that I added from and it was, indeed, 5-W-30. So I must have been smarter when I bought it than I was when I was writing about it. Other than that, I'm pretty sure the place where we get the oil changed fills it per manufacturer's specification.

Anyway, that's it. I've owned a lot of old cars, and no "miracle in a can" ever did a thing for me before. I was so surprised that it worked that I figured I'd post it. This is an odd case, for sure -- oil consumption due to buildup of carbon on the rings. But I can't be the only guy this has happened to. So I thought it might do somebody some good.

I'll check back in another 1000 miles and report on the oil consumption.

 

That was exactly my thinking. I knew one bottle wasn't going to do much. And I figured if I didn't buy it in advance, I'd probably have said to heck with it after the first couple. Or forget, or not bother to stop by the auto parts store. So I committed, bought four locally, bought a case of six off Amazon. And so it only took six, not ten. I'll use the rest up eventually.