Will a thicker engine oil burn less? How to get engine to burn less oil?

2005 Camry.

My engine burned about a half quart of oil during that past 1k miles. I used Engine Restorer for the past couple oil changes, and it doesn’t seem to be doing much.

I changed the PCV valve and that did seem to help.

My car currently takes 5W-30 oil. A friend said that if I use 10W-30 the engine will burn less. Do you agree, and do you think it’s safe to do this?

Do you have any other recommendations for taking care of this problem?

I put a new catalytic converter on 14k miles ago, and so far I’ve had no code come up for it despite the frequent oil burning. How long do you think this can go on?

I may try using Lucas Oil Stabilizer as well.

!0W-30 oil is thicker during cold starts. This means it takes longer for the oil to reach engine parts, which increases engine wear.

The car is almost 20 years old. So keep using the recommended oil and add when required.



I take responsibility for the maintenance on a friend’s vehicle, and he had a 2005 Rav-4 with the same oil consumption problem. Changing the PCV valve helped to a small extent, and Restore helped to an equally small extent.

By the time that it got to consuming a qt of oil every 300 miles, he decided to just dump it and buy a new vehicle. The catalytic converter had not yet gone bad, but it was only a matter of time.


1/2 qt in 1,000 miles is … well, sort of a lot. But not an insane amount. I’d live with it, check the oil at every gas fill-up, and just keep it inside of the dipstick marks

Your friend is nuts. Explain this to them: the low number on a oil viscosity designation is when the engine is cold. (“W” actually means “winter” - aka cold - as far as I know). So unless you only run the car for like one mile at a time it is not overly relevant.

I.e. 5W-30 and 10W-30 are EXACTLY the same viscosity once you’re up to running temps - which takes all of a few minutes (or less) of driving. If you want to “experiment” with oil weights for a while try a 5W-40 for a while. That can cause it’s own problems, but the 2nd number is the key, not the first.

I’d say burning a quart every 2000 miles means you don’t HAVE an oil burning problem.

Come back when it is a quart every 500 miles.


Really? This makes me feel better. Do you think the catalytic converter has a chance at a long life?

Yes, really. I’ve never had an oil burner, but a lot of manufacturers will tell you that a quart per 1-2K miles is “normal.” (I always thought that was weird, but it’s a thing). And if the exhaust was so rich as to be a problem for the cat, you’d be likely to get error codes for something like running to rich.

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So, you think I already would’ve gotten a code already if the oil burning was too much?

I got a P0420 on my previous cat. After that, I changed the PCV valve, and started using better oil along with engine restorer. So far there’s no problems with the new cat after 14k miles.

How many miles on this Camry?


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Ahhhh…a previous P0420. Yes, then you my be burning enough to damage the cat. They’re not wear and tear items - as in, if everything upstream of a cat stays right, then it really ought to last indefinitely. They’re completely passive. So if they fail they’re either being contaminated over time or got compromised by some period of severe misfiring.

So when I added qualifiers like “probably” or “likely” it was because a car can have issues that are not great for the cat, but not bad enough to set codes. That doesn’t make sense to me - but I’m not a programmer of OBD 2 software. The shop that did the work for the P0420 should have been wondering about this…

Back to the initial question…changing to 10W-30 won’t help.

Run a dry then wet compression test on it…
I’m curious what it looks like under the valve cover. lol

If the oil control rings are shot, don’t think any snake oil is going to help… I’ve seen thicker oil help with piston compression rings and main bearing noise (knock) but don’t remember it helping much with oil control rings… You might try replacing the valve stem guide seals and even check for any play in the valve guides, but it really just sounds like it is time for an overhaul, reman, used or new engine, or just upgrade to a newer/different car…

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On a 19 year old car that uses a quart of oil every 2000 miles? That level of oil consumption isn’t enough to warrant a repair on a 5 year old car.

Just check the oil regularly, add the correct oil as needed, and drive on. Oil is cheap.


The odometer reads 115k, but the engine in there is a used replacement engine. According to my mechanic, it should also have about 115k miles also, but Ican’t say that with certainty.

A lot depends on if it’s getting worse. So I’d keep track of the oil use and think about doing something when it gets under 1000 miles a quart. Could take years.

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Yeah, my mind was processing a quart every 1000 miles for some reason, maybe cause it was 1am and I was about to fall over… lol

I’ve had and still have some high mileage engines and none of them burn oil unless I go past the mileage time due for their oil change… My daughters 2002 Corolla when we traded it in was running very strong with 205,000 miles on it and did not burn oil between the 3,000 miles oil change serves, my 2006 Corolla with over 180,000 never burned oil either… But I also don’t (except for her 2017) ever use full synthetic oil and always from about 75,000 miles and up, I always use High mileage oil…

My question is, what has been done to this poor little Camry that it is on it’s 2nd engine and already having issues with only 115,000 miles on it, that is only break in mileage on most Toyota’s… lol

Yes, I do. Not as long as the original but if you do some longer highway drives every now and then, it should help keep the cat clean.


Nobody can predict this precisely, but… probably yes.
After increasing oil consumption for about 1 year, my friend’s Rav got to the point of using 1 qt every 300 miles or so, and the catalytic converter was still good. Probably not for long, but after all of that abuse it was still functioning properly.

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Your mechanic has info that verifies your motor was replaced? Did he do it? Did you do it? I think it’s odd to find a reliable Camry with a lower mileage replacement motor.

One quart per 2000 miles isn’t excessive oil consumption. Esp for a 2005. I think your best bet is to use the oil Toyota recommends, and not add anything to it. Other than that, keep it topped off between changes & perhaps increase the frequency of oil and filter changes. Seems unlikely the oil consumption rate is related to the prior cat failure & replacements. The cause for that is more likely to be an incorrect fuel to air mixture. Suggest to focus your shop’s attention on making sure that parameter is within spec. Do you have this car emissions tested? If so, what is the HC tailpipe measurement?


If the engine uses enough oil it changes itself. :wink: