Any luck slowing oil burning with a stop leak (lucas, blue devil, bars, etc.)

STP?

-Graeme-
2004 Prius with >190,000 miles.
Sent ?.

 

well...the thing is our prius have higher than "common" high compression engines.

Most common is 10 to 11:1

we have 13:1

oil burning is just a part of the nature of high compression engines. Just do not make the oil tooo thick. there's a trade off



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It’s basically the same parts as a scion engine that does run continuously so I have to disagree with you. Do the scions and Yaris 1.5 engines burn oil? I know that some Corolla 1.8’s have massive oil burn problems. Worse than their gen 3 Prius equivalents.

 

It may be technically 13-1 I’m not sure, but the engine never gets close to that due to the Atkinson cycle pushing some of the fuel - air mixture back into the intake manifold during the compression cycle. No engine could run on 87 octane fuel at that compression without something to suppress detonation, like water injection.

 

Good point.

It is a claim by Toyota, but as always trust but verify

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It's not a huge deal, my car was bought at 215k and burned a qt every 1000 miles until 270k when the headgasket blew. Those products are prob really thick oil intended to thicken your existing oil. Keep an eye on the cat when you get a p0420 code it's time to get a cheap eBay replacement as the burnt oil will clog it. That's probably what ruined my headgasket. But if you keep the oil toppedup it will run fine.

 

Which begs the question, just try going to a thicker oil first? It's a more controlled experiment I think.

 

yup, totally in agreement there. But if you get cold winters like we do, at some point you have to decide what is more important, burning oil or having that cold start protection. So I ran 5-20w synthetic in the winter and topped up weekly, since I put on about 130 miles each day. Generally even though your engine is burning oil it will not fail unless one of the following happens

-run low of oil/spun bearing
-fouled spark plugs from oil deposits
-plugged cat

which you have to weigh the cost/benefit of topping up oil, changing plugs more frequently, and possibly changing the cat. FWIW with a junkyard engine you don't know what you're going to get. I swapped a junkyard motor with 76k miles on it, it runs great but it also burns oil too. So my preference is just to keep driving the car and don't fix what isn't broke.

 

Also note that the compression ratio is actually 9.5:1, while the expansion ratio is 13:1. Because of the Atkinson cycle, it is possible for them to be different.

 

OK, gotta ask:
Why are you stuck on using Liquid Moly in this situation ?
Do they claim it will help with oil burning ??
I don't think so.

 

It is only 1.6 qts between the top and bottom dimple. If you were down by 2 qts, it wouldn't even register on the dipstick.

It looks to me to be about ½ way between the dimples, so 0.8 qt low.

 

Well it is kind of important that you mention which specific member of their product line that you are talking ABOUT.
Because their original basic "super-slick engine treatment" certainly won't help with oil usage.