Oil Consumption

look at the puff of smoke when engine starts.

This may be due to worn valve seals. 6 years enough to turn them into glass. Simple $300 replacement of worn seals with the best quality nitrile rubber you can buy almost doubles the life of engine.

2nd if you used non-synthetic oil it is possible the oil rings are stuck due to burned oil deposits. Here is the way to clean it out:
- buy oil flush
- remove spark plugs and pour it cylinders
- let it soak overnight, add if needed
- add what left to crank case
- warm engine
- change oil
Also put new cheap oil filter before you do flush, just to be on safe side.

3rd switch to synthetic oil. Drive for ~500mi (probably more on Prius) and then replace filter. Do not use high quality filters like Mobil-1, PureOne, etc for at least 2-3 oil changes, they clog faster, and do not attempt long oil intervals during this time.

It is not a miracle but it will help to get most of whatever life left in your engine. Unless you have a bad leak, if you've gone to 1-2qt consumption, you are looking at 10-20k at most before you need new engine/full rebuild, YMMV

 

FYI, AMSoil recommends against using its flushing product on hybrids:

AMSOIL Engine Oil Flush Procedure

Consumption can go on for a very long time. Toyota specs 1L/2000KM as the threshold for powertrain warranty replacement (1 qt per 1200 miles).

I suggest going immediately to option #3 first-- fill with synthetic, specifically Royal Purple. 2 fas 4 u, the guy with the 400,000 mile car, reported a drop in consumption when switching to Royal Purple over Mobil 1.

If all else fails, salvage motors are incredibly cheap. One guy bought one and installed it for $225. Probably $1000 or so to have a shop install a salvage one.

 

Car Bibles : The Engine Oil Bible

it is up to you if you don't wanna put it in crank case, but pouring it in cylinders overnight works, the deposits get burned and the stuck rings released. Also did not mentioned you need to crank engine for a few sec before re-installing plugs, otherwise you risk hydraulic lock if anything left there.

Also if you do not flush engine and put synthetics it is safer to replace filter a couple times, maybe after 500mi and then after 1000.

Never used Purple but had seen engines with Mobil-1 opened after 70K and they looked sparking clean. It may be not the best synthetic but it sure cleans.

All mfg have similar guidelines to cover their arses and reduce warranty costs.

 

I think it is very important that a person trying to desludge one of these engines proceed cautiously. But I do like the idea of letting the stuff sit overnight in the cylinders for an engine whose driver thinks that the consumption is excessive. I think sludged rings is likely a bigger problem than worn valve seals. Another thing to keep in mind is that the engine can be cranked slowly for just a few seconds with the injectors closed using the compression test procedure with a bidir scan tool.

The big question is at what point a driver decides that the consumption is too high. For example, my ex-in-laws had a rebuilt 390 that burned a quart of oil for every tank of gas, and they were fine with it.

 

Hi Frank06,

Don't panic. This talk of a salvage engine seems totally premature to me. Unless, of course, you've run it out of oil and damaged it.

Don't do anything rash. Put in a fresh change of high grade oil and track the consumption. Remember, as oil gets old, it get contaminated and it breaks down. This leads to a faster rate of consumption.

We don't even know how much oil uses! How far does it go on a quart of oil? Only check the oil on dead flat ground. Only check after setting over night or when fully warm and has set for five minutes.

How often is the oil changed? What brand and type is used? Have you tried a "High Mileage" oil. I've had good luck in my old clunkers (not referring to my Prius).

My 2005 uses about a quart every 5K to 7K miles. I consider that to be insignificant. I would consider a quart every 2k miles insignificant. When oil consumption increases to a quart every 1K, then you know there is some wear.

The most important thing is not to let it run out of oil. Check it with every fill-up, just like the old days.

Again, don't panic. Engines can use a little oil and still have a lot of life. And if it is in fact using more oil, don't extend the oil change interval beyond 6 months of 5K miles. Engines that use a little frequently have more blowby past the rings and contaminate the oil faster. Hence they need more frequent changes.

I think you're probably fine. Just remember that it's not brand new and may need a little TLC.

Enjoy the car, Dan

 

Hi Frank,

1. Given your description above, it is clear that your engine is showing some signs of wear.

2. However, so what? It's not realistic to expect the engine to remain in as-new condition forever. 135K miles is heavy usage and would be near end of life for many automobiles.

Add a quart of 5W-30 oil as needed, and carry on. Just don't let the engine oil level drop below the lower dipstick dimple, unless you really want to install a replacement engine soon. Note that the difference in oil level between the two dipstick dimples is ~1.6 quarts.

 

Regarding engine sludge, you need to remove the valve cover to see that on the valvetrain, if there is any sludge to be seen.

It would also be a good idea to replace the PCV valve, which is bolted into the end of the valve cover on the side closest to the inverter.

 

+1!

if not replace at least clean it with carb cleaner

 

Hi Frank06,

Let's hope you have built up a lot of good karma and are very lucky. Otherwise, start saving for the used engine and installation.

You did not mention the dreaded triangle of doom previously. This is not a good sign.

I don't say this to be overly negative or place blame. My purpose is to turn a potentially expensive experience to a lesson that may help others. If adding oil stopped the "red triangle", then it was probably the low oil pressure light. There is no low oil volume light, only low pressure. This pressure warning is set very low because the oil pressure can drop very low on any engine when it is hot and idling. On my ISUZU, the low oil pressure light comes on at 4 to 7 PSI. At driving speeds, the pressure should be 35 to 65 on my ISUZU(at 2000 RPM's) with a hot engine. My memory it that most Toyota have the low oil pressure warning activated at about 4 PSI.

If low oil pressure triggered the "triangle" then your oil level had to be very low to cause a pressure drop. Most cars have an oil pressure light. Many people wonder why, because it usually only comes on to signal that you've just ruined your engine.

If the engine is damaged no amount of tinkering with the PVC valve or flushes will do any good, but you don't have anything to lose either. You can also try thicker oil, and high mileage oil, to reduce consumption, all the way up to 15-40 depending on the outside tempature. Just go up one step at a time. I'd start with 10-30, 10-40....

Just remember the Saturn owner's motto: "Saturn's don't die, people kill them. Check the oil!"

Best of luck, Dan

 

I totally agree with the above. In fact I think that every case that I've read about in these forums of very high oil consumption has started out with someone running it down to the low pressure warning.

Sure, that fact that it got low enough to trigger the warning means that there must be some consumption, but it is normal that as the car ages that the oil consumption increases gradually.

What happens in these cases however is not a gradual increase but often a step change after the low oil pressure event. People often get the causality confused in these cases and assume that the high oil consumption started before the low oil event but this not necessarily the case. Just some very mild oil consumption in conjunction with an underfill (or perhaps even some substandard oil) can cause the initial problem. But as Dan points out, once the warning comes on you've got basically no oil pressure and you can literally put on the equivalent of 100,000 miles of wear in 10 minutes under those conditions. (Actually even before you get the warning you're probably getting poor lubrication due to the oil condition, which is usually pretty lousy with the contaminants starting to get fairly concentrated, by the time it's that low).

The bottom line is that we should all check our dipsticks fairly regularly, even if we haven't previously needed to top up between changes. The trick is to catch any mild increases in oil consumption before they cause a bigger problem.

 

Yes, it's a pet peeve of mine when I sometimes hear about people not checking their oil at all, thinking that when the oil (pressure) light comes out, that's when they should add some. I tell them: no, it's not an oil level light. It's an oil pressure light. Your oil is way low by the time that comes on and you might've damaged or ruined your engine by then.

All of this was back before any cars had any sort of oil electronic oil level monitor. Almost all cars still don't but the most famous examples of cars that have this are some newer BMWs where they ditched the dipstick entirely in favor of an apparently unreliable sensor, leading people to overfill their oil due to a false warning. More details at http://priuschat.com/forums/other-c...es-cars-have-no-dipstick-starting-2006-a.html.

 

If in fact you only had to add 1.5 quarts to bring the oil level back up to the top dimple on the dipstick, then the engine oil level was not seriously low.

The PCV valve is bolted on and you will need to remove the engine wiring harness that runs along the valve cover to gain access.

The OP does not report visible exhaust emissions or driveability symptoms so I would say it is premature to assume the engine is "ruined." If the only issue is that he now has to add 1 quart of oil every 1K miles this is not the end of the world.

 

when valve seals go out, there is not much in a way of visible exhaust emission.. you only get it with engine braking and on restarts, esp on warm restarts. Oil sips through seals, just enough for a puff of smoke on first 2-4 revs.

This is on non-hybrid ICE, but Prius ICE restarts many times.

 

I think we are all in ageement here. Bacically, Frank06 needs a good test of oil consumption, I recommend a fresh change, and then he needs to check the dipstick on a reqular basis. We are all hoping for a good outcome.

I would like to add that an engine can consume a lot of oil without visible emissions or drivability issues. I've owned a lot of junkers and still own one (an old Isuzu Pickup). I have engines that use as much as a quart every 600 miles and don't have visible emissions or obvious problems. Get down to a quart every 400 miles and you almost always have visible emissions.

All the best, Dan

 

compression test?

 

it is not gonna show much unless engine gone south completely and smoking like chimney. Would not hurt either.

Modern overhead engines fail in such sequence:
1) valve seals -> some oil consumption
2) clogged due valve seal consumption oil rings -> more oil consumption
3) if left neglected -> worn bores/rings and alot more oil consumption.

it is worth trying the ring soak and then valve seal conditioner additive; it may actually cure it somewhat w/o seal replacement.