Help! car eating a lot of oil.

The sad thing, though, is that a _lot_ of people badly abuse their cars. I got 280k miles on a Corolla myself, but I also broke the engine in properly and changed the oil religiously. Too many folks don't do either, and around

100k is when their folly begins to show itself. (The fact that the things can run that long _without_ proper maintenance is a testament to their design.)

--scott

There is no way your engine doesn't use oil. The design nature of piston engines guarantees that some oil is consumed. You are confusing no change in the level shown on the dip stick with a lack of oil consumption. I had a very old tractor that actually "made" oil between changes. For grins, send off a sample of oil for analysis at your next oil change. I imagine it will show considerable contamination. This doesn't mean the engine is worn out, just that it is normal.

One of the ways Toyota is able to obtain outstanding gas mileage numbers is through the use of low tension piston rings. Less friction, better economy, less wear, all good things. But this also means more blow-by under some conditions (not so good). It is my unproved belief that Toyota does a very good job of controlling bore diameter. This means they can also specify tighter tolerances on the piston rings. This allows for lower tension rings. Old American engines were not as carefully made and they specified stiffer rings to compensate for less control over the bore diameter. This resulted in more friction, poorer fuel economy, blah, blah, blah. The down side of using lower tension rings is that if you don't care for your engine, ring and bore wear can rapidly reduce the tension to the point that blow-by becomes a problem - leading to sludge, excessive oil burning, etc.

I've never actually worn out a car or light truck engine. I think the most miles I can verify on any vehicle I've personally owned was 150k. We have an old Dodge D600 Truck on my farm with a broken odometer that may have more miles, but who knows. At least for me, it has never been engine failure that induced me to replace a car. Now farm tractors are a different matter. I have one tractor that has so much blow-by if pushes oil out of every crack it can find - and the tractor just has an old road draft tube instead of a PCV valve. The engine probably could stand a rebuild, but with today's prices, it is not worth the money.

Ed

I'm confusing nothing. And, I was exaggerating just slightly. When you buy a quart of oil as a gift for your new car, and it's only 1/4 gone three years later, that's as good as nothing, especially compared to what the OP is describing. See what I'm saying? 1/4 of a quart. 8 ounces. Three years.

200k miles.

messagenews:465d9a5e$1@kcnews01...

The fact that you didn't add any oil doesn't mean your engine isn't using oil. Have a sample checked. Even if your engine is in perfect condition, after 3000 miles, more than 2% is something other than the original oil (water, unburned hyrdocarbons, sut, etc.). For a severly worn engine the percentage of other stuff can be significant.

Think about it, if your oil control ring scrapped the cylinder walls dry, what would lubricate the compression rings? If the valve seals were perfect, how long do you think dry valve stems would last? If a little oil didn't coat the seals and escape, how long would they last? What is that stuff coating the inside of the PCV lines and fittings? Oil is constantly being consumed in order to keep pistons, rings, valves, and seals lubricated. Some oil escapes via the PCV system. The amount might be small, but it is not zero. Engines that show no change in the oil level are still using oil, they are just replacing the oil consumed with stuff that escapes past the piston rings. I've had plenty of engines that never need oil added between changes. Nothng special in that. I've also had engines that needed a quart added between changes. That never worried me either.

I just took a sample from my SO 2007 RAV4 when I changed the oil. I'll be curious to see the level of contmaination. It should be low, but the oil was a nasty black color. This is something that I wonder about. I've had a few cars that will turn the oil black in just a thousand miles or less. Other cars (in particular a Saturn Vue I owned) seem to keep the oil much cleaner. I don't know if this is a result of the PCV system, or the oil filtration.

Ed

Question:

Is 8 ounces less than 12 gallons? I'm honestly not sure, so I'm looking for your expert answer.

I am missing your point. I never said your car was buring a lot of oil. I just pointed out your car is burning some oil, even if you don't actually add any. Excessive oil consumption defintinely indicates there is a problem. The reverse is not necessarily true. It is possible that your engine is in really bad condition, even if you aren't adding oil, but I suspect this is not true in your case. What qualifies as excessive oil consumption is subject to debate. I am sure Toyota has a specification for this. I don't know what it is, but figure it is somewhere in the 1 quart per 1000 to 3000 mile range. It is defeinitely not 1 qt per 240 miles. This is excessive in anyones book.

Ed

I disagree, and suspect it is being burned steadily, and the smoke is being suppressed by the catlyst. If it were *leaking* that much, there'd be a film of oil all over the underside of the car and even on the rear end where the air from under the car recirculates. I've had MUCH smaller oil leaks than that leave oil freckles all over the back of a car.

The cost to repair worn rings varies by shop and local labor rate, but my wild guess is somewhere between $500 and $1,000. Unfortunately, if the rings got worn due to extended oil change intervals, there is a good chance that the crankshaft, rod, and camshaft bearings will also be worn, in which case a replacement engine may be less expensive. I'd start by looking for an oil leak.

Horse shit, unless the Dodge had the Mitsubishi 3.0 engine!

If it falls in the "sludge monster" years, then its no surprise at all.

Complete engine tear-down and overhaul- might as well do everything while its that far apart. On the order of $2k, depending on whether the block is so badly ridged that you need a re-bore and oversized pistons as well (likely, given oil consumption this high).