Gen II Burning Oil?

Newcastle huh? I didn't know anyone owned a Prius in that town.

I work in Auburn and there are Prius everywhere so I'm just giving ya hell.

 

Most likely the type of oil consumption described in this thread is due to gummed/sludged lower oil control rings on the pistons. Technically this is hard to confirm as it doesn't show with a compression check. The best confirmation is to run some fuel system cleaner and see if it corrects.

What brand of gasoline are you running? I would recommend Chevron with Techroline or something similar with a cleaner additive like Chevron or Shell.

To correct the problem you can try adding a bottle of Techroline to the next 5 tanks of gas. This will be a lot stronger amount than what comes added in the Chevron gas and will clean the sludge buildup. The amount of the cleaner that comes added to fuels is only enough to prevent sludge accumulation and not really enough to clean up a substantial sludge buildup.

This problem may also be affected by an engine that is not ever driven hard. This would be typical of a Prius where you are always trying for high mileage. It doesn't hurt to occasionally get near full throttle redline and this helps to heat and blow out the carbon/sludge.

I don't really recommend treating a new quart of oil every 1000 miles as an oil change. When this gummed up ring problem is present the oil gets dirty faster and still needs a 5K complete change.

The technical explanation. An ICE piston has 3 rings, the top 2 control compression, the bottom ring scrapes the oil off the cylinder wall as the piston goes up and down, to keep it out of the combustion chamber above. The cylinder wall is bathed in oil from the crankcase below. Piston rings float in their grooves in the piston so they can closely follow the shape of the cylinder wall, this allows a better seal. Cheap gas tends to contribute to sludge buildup that gums up the oil control ring and groove. The ring gets stuck in one position and does not float in it's groove. This allows oil to get past and burn in the combustion chamber. It's usually not enough to cause visible smoke but enough to burn a quart per 1000 miles.

 

Nice advice, thanks for coming back to this. Is that piston in the photo from a Prius?

- D

 

most plausible explanation. Also kind of explain the "sudden" on set of oil consumption: stuck oil rings. So, fuel treatment to fix oil consumption, interesting.

Thanks

 

the photo is an advanced level of stuck rings, it probably won't get this bad in a Prius but the rings do stick and start burning oil long before this stage. The photo if from a Google image search but I've seen pistons like this working on Nissan's and Honda's.

 

Wow this is new to me. So not all gas sold are equal in quality? I thought they all come from the same few big refineries and the branding just adds cost similar to the case of vitamins. Aren't there some kind of regulation requiring all gas sold to contain sufficient detergent? Would used oil analysis show sign of sludge buildup? Thanks!

 

The first reply asked what kind of oil you are using. Brand, viscosity. Start there.

BTW, you can comfortably ignore advice to use 5W-50 oil. It's not designed for your car.

 

Also keep in mind that generic North American API oil standards do little to prevent ring land deposits and resultant ring sticking. Oils that meet European ACEA standards, especially A3-B3/B4, and diesel service oils (CH-4,CI-4, CJ-4 etc), are designed to specifically address ring land fill

 

You did not mention what kind of oil you are using. I work at a lube and tire center and if you change to synthetic oil late in life on the engine sometimes you will experience oil use. Let us know.

 

I'm driving a 2006 Prius with 160,000 miles on it. It's using almost 2 qts. between oil changes. I'm using NAPA 5W30 Synthetic. I did a differential compression test and all the cylinders were around 78 over 80 psi which is good (for an aircraft engine anyway--don't know what is normal for a Prius.) Attached is a picture of one of the plugs. Seems to be burning lean if anything. I am finding oil pooling in the bottom of the intake manifold. It can be seen by manually opening the throttle plate. (See attached photo, sorry I couldn't get it to focus on the oil). Although the old PCV valve seemed fine, I changed it several weeks ago as a precaution. Today I still found oil pooling in the intake manifold. There are two vent hoses from the valve cover to the intake manifold. The hose with the PCV valve goes below the throttle plate and the one without the PCV valve goes to a point above the throttle plate. I'm not sure what keeps excess oil in the valve cover area from draining down the hose without the PCV valve. Last week had a cyl. #2 misfire code,--may have been connected to the excessive oil getting sucked into the intake. It has not repeated after clearing it. Any suggestions would be welcome--just don't tell me that up to a quart every 600 miles is not excessive. I'm considering swapping with a 30,000 mile engine from the wrecking yard.

 

A slight amount of oil pooling in the intake manifold is pretty normal.

Regarding the DTC P0302, how long have the spark plugs been in service?

I won't tell you that consuming a quart/600 miles is not excessive, but if that is the only problem that you have, it seems unnecessary to swap engines (like using a sledgehammer on a fly.) Much easier just to add a quart of oil periodically...

 

2 fas 4 u, the guy with almost 400,000 miles, found a reduction in consumption by using Royal Purple.

 

Less than 20,000 miles

 

If the oil is somehow finding its way into the intake manifold I don't thing changing the brand of oil will make any difference.

 

If the oil is somehow finding its way into the intake manifold I don't thing changing the brand of oil will make any difference.

Some oil in the intake base is common in these engines, unless it's filling up the intake, it's not your problem. Changing the brand could make some difference, for what its worth I use conventional oil, different brands I've bought in bulk, and get over 6 k per quart easy in my higher mileage prius.
I would try the suggestion from PriusTech who says oil consumption is usually due to the oil control rings being gummed up. -------------------quote.-------------------------
To correct the problem you can try adding a bottle of Techroline to the next 5 tanks of gas.

 

It seems like a lot more than "some oil in the intake base". One problem with old Continental aircraft engines is that they lose a lot of oil out of the breather. For their aerobatic engines Continental increased the length of the breather tube so that oil getting slung in the crankcase would not get slung out the breather elbow which normally is flush with the inside of the crankcase. See picture below. I live in the foothills south of Yosemite. Could it be that all the curvy roads here contribute to oil getting dumped out of the valve cover and into the intake manifold? I don't know how much oil is sitting on the top of the cylinder head normally, but if there is a significant amount it seems to me that it could easily find its way into the intake manifold during right turns. Maybe an extension onto the pipes going into the cover might help eliminate this.

If the oil control rings are gummed up I would have thought that I would have been getting air leaking past the rings during a differential compression test but I guess if the top two rings are sealing this would not be the case. I'll give the Techroline a try as you suggested. Thanks.

 

Jut checking the obvious first. Are you 100% sure that you're not overfilling the oil? Serveral people have reported getting excess oil in the intake if the oil is even just a small amount over filled.

Ok I'm pretty sure you know to keep the oil between the bottom and top dimples on the stick, but just checking anyway.

 

I don't know, I think spending some extra bucks for a gallon of Royal Purple is worth a try vs. hundreds of $$$ and a weekend doing an engine swap.

 

2-3 QTS per 3000-5000 miles is plenty of oil.
The 98 Suburban 216,300 miles uses much less than that-and it leaks a bit.

A question- I rarely see blue oil smoke nowadays-even from obvious clunkers(late 80's domestics etc-there aren't any 80's VWs left on the roads,so not like I'm picking on the BIG 3).
Is the lack of smoke because the cat con completely burns the oil that gets past the rings??

In pre catcon days it was very common for clunkers to leave a blue smoke trail.
I would think 3 qts would leave a trail-unless it is being burned by the catcon-which I think it is.

Charlie
PS like others said-try some gas treatment-techron etc- many GM fans like Seafoam?? GM makes a top cyl cleaner also-they have a problem with gunk building up above the 5.3's top ring-makes a piston slap noise.
Forget changing out a motor-oil is cheap-and a used engine is a used engine.

 

Can't be good for catcon or emissions? One would think this level might give inspection pass issues.