Oil Consumption

Shark, is there any difference in feel between a cold start and a warm start? Cold start vibration could indicate bearing wear, which precludes valve seals as the problem. No matter what the source is, if consumption is stable at 1/2 quart with each tank of gas, you might was well drive it until it dies.

 

I notice no difference..

 

Menards (if you live in the midwest) puts Shell conventional oil on sale all of the time for $1.99/quart.

Kmart has their cheapy brand too (Super S or something to that effect), a semi-synthetic that goes on sale for $1.84/quart every now and then.

Walmart has their Supertech brand that is $2.47 a quart for conventional.

I'd stock up on a good cheapy conventional oil and keep adding 1/2 quart every tank until the turd plops for the last time.

 

I had the same problem - only worse - my 2008 Prius (with 185,000 miles) suddenly started to use lots of oil - like a quart every 300 miles. I didn't see any smoke either. I was using a non-synthetic oil. I read the entries in the prius chat about putting engine flush in the combustion chamber - so I gave it a try. I removed the plugs and put 2 oz of NAPA engine flush in each cylinder overnight. In the morning, I removed the excess flush with a small wet-dry vac with kitty liter in the vacuum dirt holder and a plastic straw duck taped on the inlet hose - so I could vacuum inside the combustion chamber. Most of the engine flush passed through the rings overnight into the crankcase - I only recovered maybe an ounce. I added the rest of the engine flush can to the crankcase and started it up, ran for about eight minutes until warm.

It smoked alot for a minute or so when I first started it. My oil consumption is back to normal - about a quart every 1500 miles. I switched to a synthetic oil and hopefully, the oil rings don't stick again. regards james

 

amazing, thanks!

 

What kind of engine flush you used? Is it very thick? Can you post a link on ebay, autozone.com?
I have a bottle of Motor Flush by Gunk. Is that something similar to what you used?

Thanks!
Allen

 

I have been talking about piston soaks here for a long time. I had good experience with them in corolla burning oil. I would go from 1 qt every 1500-2000 miles to zero. But the consumption would creep back after 5000 miles, even with synthetic oils. I made a habit of doing that every 5000 mile oil change. Unfortunately if the oil pistons holes are plugged up with hard carbon, nothing can clean them short of drilling out. However, piston soaks will clean the ring groves and prevent rings from getting stuck, there is no question about it.

The usual response here has been: snake oils, LOL.

 

1 quart every 300 miles? How long has this been happening? You can't even go an entire tank of gas before losing a quart. ...wow

 

The consumption increased dramatically over about a 6000 mile interval - about a 5 month period. I used NAPA brand flush - I'm sure Gunk brand is nearly identical. The consistency was about the same as SAE20W oil.

 

I've recently discovered that my 2009 is starting to use oil. I checked the oil about 500 miles before I did the 95K oil change and discovered that it was down a quart. It has never used any oil before up to 90K. I have changed the oil religiously at every 5K per the manual, always used either Wix or NAPA Gold filters and Chevron 5w-30 motor oil.

This car is my daily driver and I run about 40 mile per day round trip to work and back. Gas mileage is running between 53 and 56 mpg depending on ambient temperature. There are no leaks anywhere on the engine and no blue smoke either. I'll start with the PCV valve and then maybe some Seafoam and see if the consumption settles down.

Since the change I have put on about 500 miles and the oil level has not dropped yet. I'll be checking it weekly to see if there's any usage.

 

The consumption seems to be quite normal and isn't all that much. Toyota considers up to 1.1 quarts every 600 miles to be "normal".

I wouldn't add anything to the engine until your usage increases significantly. Engine additives can do more harm than good sometimes. Just top off as needed for now.

 

That's only one quart every 5k miles. You may find it uses even less if you top it off before it gets too far down on the dipstick.

Exactly. The simple approach is the best one in this case. This one is solved by just checking the dipstick every 1k to 2k miles and topping off as needed.

 

I'll keep an eye on it, thanks for the recommendation.

 

"Eye it like you've been eyeing my weave" that's good advice to all prius owners to keep an eye on that dip stick!

 

Wow...so. This is what happens when Prius drivers go unsupervised? LOL...
I have to tell you, that on the rare occasion I end up here trying to solve a difficult Prius issue, I occasionally end up here looking for a nugget, and see a lot of misinformation kicking around. So, a few things:
1. Mobil 1 is a necessity for the extended oil change times these engines are capable of. Before non-synth oil goes bad, it loses viscosity, usually. But on these cars, it starts turning acidic. Synthetic won't turn like that.
2. Royal purple has a strong correlation to skin cancer. Don't ever touch it with your bare hands.
3. "Nothing causes a misfire except worn valve seals"?
Worn guides causes misfire. Worn seals cause oil infiltration to the combustion chamber, indicated by brown/black spark plugs and oil consumption. If the guides are worn, it will displace the seal on even with brand new seals.
I have been suspecting that the guides are wearing prematurely on these engines because of their inability to maintain operating temperatures in cold weather especially. Stem to guide clearance is only tight enough to not displace the seals when it is at full operating temperature, or on a sliding scale toward operating temperature. Loose/worn guides allow the valve to not sit squarely on their seats, causing misfire. I have been watching the really heavy temperature cycling on my Prius cars, and my 400h for a few years now.
Valve adjustment, always overlooked in a reliable engine family, is important to efficient valve timing, and timing chain replacement is supposed to happen between 120k and 150k. Stretched chains or late valve timing due to excessive vlave lash can increase cylinder pressure at lower rpms, and will cause the knock sensor to pull back timing in the ecu to prevent ping and abnormally high cylinder pressures, as well as leave higher emissions, cause misfire which washes the cylinder wall oil film off becuase of unburned fuel left in the cylinder, further compounding the engine's ability to maintain combustion sealing, rings/valve seats will all wear prematurely. Also, many people don't know that using a higher octane fuel than high 80's ALONE can cause cylinder misfires.
I have noticed that usually the misfire is engine wide, not relating much to any one particular cylinder, that is why they most often set a "Random/multiple misfire" code. Sometimes misfire in one cylinder is so bad that it slows the rate of crankshaft acceleration for the next cylinder in the firing order enough for a misfire to be triggered there as well.
I suspect that a proper valve lash adjustment and a timing chain replacement at the SCHEDULED INTERVAL...may prevent misfires on engines beyond 150,000 miles. The intake manifold change is mostly bunk I feel, because I have seen engines in the 150k range misfire after the updated intake change.
That's my 2¢
God I love these cars

 

okay, but how do we know this isn't miss info?

 

My 2005 has 180k miles now, not misfiring and not using any oil. The timing chain have never been changed, and valve seals are original. What am I doing wrong?
Alex

 

I think is has a lot to do with operating conditions, and how well the engine was maintained. Engine oil becomes acidic as it ages, and the tendency for some is to allow oil changes to go 5,7,10k miles before changing the oil, which may be as much as 6 or 9 months for some of us. Synthetic oil doesn't break down like non-synthetic. 3-5 months is about the limit for engine oil. It also may have a lot to do with how it is driven, which ever way causes the most stresses on an engine, which MAY NOT be about driving gingerly. Engines are built for being used, through their whole rpm range. When that isn't done regularly, carbon deposits form and can cause misfire from the resulting increase in compression pressure, which would cause misfire on low octane fuel. Conversely, high octane fuel will also cause misfire on a non-carboned prius engine. No matter what, when it comes to misfire, a cylinder leak down test, and a compression test could shine a light on things, even using a horoscope to visually determine the condition of components in the combustion chamber. These are tests that not too many mechanics (especially dealership ones) even bother to do. Dealer techs would rather wish that throwing some parts at a Prius will solve the issue. And Toyota won't pay them for a proper diagnosis if it isn't recommended by corporate for a given service bulletin. If something is found during one of these tests, major engine service would need to follow, with the easiest being a valve lash service (about 3 hours given the parts counter has the proper shims), to a cylinder head service with new guides, seals, valve job and gaskets. Deeper would bring piston rings into it.
Again, I think more Prius engines would be like yous, with no misfire or oil consumption if people changed the oil every 3-5 months. No matter what, valve lash service is almost NEVER done on the engines because it is time consuming, expensive, and with no immediately recognizable benefit to most owners until they hit 150k.

 

Miss Information. Yep, there is a lot of it and it is hard to know answers to issues like this. The truth is different with every car, forums like this with engine issues often miss the mark because everyone brings their consumer experience from a multitude of shops, all with a different opinion. I happen to be a damned good engine builder, and have seen a lot of high mileage rebuilds. I think that these engines don't get the attention they need early on because the rest of the car is so well put together, people expect them to be bullet proof. No matter what, timing chains stretch and should be changed when they are put of spec. It is a #of hours run time thing more than it is about service duty or mileage. Engine cycling from one driver doing mostly in town travel, will be much different than a highway driver, and will have a completely different set of age related issues.

 

"Keeping an eye on the dipstick" is indeed a good idea, but it overlooks the reason for these cars in the first place, which is actually not about the fuel economy, it is about emissions. Burning oil is bad and causes more engine damage (to the point where parts become to worn to be put back in service), but mostly, it causes dozens of times more pollutants than when they were new, and will ruin oxygen sensors and catalytic converters.