Here's the situation:

I bought a used car and got into a dispute with the seller over various defects, including, most notably, the fact that the engine is burning an enormous amount of oil (apparently a quart in 200 miles or so). After a lot of wrangling, I am apparently about to sign an agreement with the dealer that he will fix all items to my satisfaction, and if not fixed to my satisfaction the deal is off. Of course, I don't think it is reasonable to tell the guy I can express dissatisfaction at any point in the future - obviously there has to be a timeline on it, and I am thinking of writing into the agreement that I have four business days - enough time to have my mechanic look at it, and for me to drive it around a bit. My concern is whether I - or my mechanic - will be able to diagnose whether the engine oil-burning problem has been genuinely fixed in that amount of time. I am afraid that the guy will make some superficial change (e.g. additives) that will temporarily solve the problem or somewhat alleviate it, such that it will be impossible to determine whether it is genuinely resolved in that amount of time.

So the question is whether there is some test that can determine whether the engine is burning oil, and if not whether this is due to some sort of phony-baloney additive or the like? The only thing I can think of is to immediately change the oil as soon as I get the car back (so as to get rid of any possible additives) and then drive around as much as possible, making very precise measurements of the oil level. But I am nervous about this and think to myself there has to be a better way. Surely an experienced mechanic who is looking over a car has to have some way of determining what the situation is in this regard.

In general, I am under the impression that anytime a car has a serious oil-burning problem, there is no way to genuinely fix it short of taking apart the engine, and I can't imagine the guy will do this (the car has 108K miles and was sold for $3.5K). So I think on that basis I might just be able to talk to the mechanic who fixes it and demand to know what he did, and if he says something that doesn't account for it, be dissatisfied on that basis. (I am afraid he will claim it was some sort of gasket leak - there is in fact a gasket leaking oil, but my mechanic says there is no way anything close to that amount of oil could be leaking from the leaks he saw.)

But what do I know? Not a whole lot, unfortunately. So any advice is appreciated. (Advice about lemon laws and other legal aspects are not
needed, as I have that angle covered.)

Thanks a lot!

IzzyR

 

You could run a compression check to see if the rings or valve guides are bad. That is the usual source of oil burning. You might even do a pressure check of the cooling system to make sure you don't have any leaks into the coolant. You might also look at the air filter to see if oil is getting blown back thru the intake.

Other possiblities are leaks from worn seals and gaskets.

Do you see any smoke while driving? I would think 200 miles per quart would produce some smoke.

Almost forgot, when you pull the plugs for a compression test, take a good look at the plugs. If you are burning oil it should show up on the plugs.
Good Luck,

Jim Henderson

 

that must be one good deal, if your going to go through all that trouble to buy it.
I would in my oppion look for something else.
Myself, it took me 6 or so months to find a dream of a truck 89' f250 ext cap 4x4 with a 460 and only paid 3500$ for it, and the only draw back is i have to have a gas truck
follow me hehe, anyhow good luck, i just would'nt go through the trouble.

 

If it was me I would want at least a 3 month warranty.

 

Thanks, Jim.

I spoke to the dealer and he said he will run a compression test himself to ascertain the source of the problem. So at least he is talking the good talk.

I myself changed the oil last Sunday, and it turned relatively dark after about 1 day - not like 3 months after an oil change, but certainly a lot darker than I would have expected so soon. I imagine this indicates some engine wear, but don't know just what type it points to.

I'm not sure if I should have bought the car to begin with, but what's done is done (and the warranty is only one month). I did in fact sign a subsequent agreement with the guy that he has to repair it "to [my] satisfaction" and I suppose I could use this lingo to weasel out of the deal altogether if I wanted to, but I'd like to be straightforward, and if this guy does deal in good faith and repairs it honestly, I wouldn't like to go back on my word.

 

You should be able to get him to tell you what he did to fix it. If he didn't go a good amount of engine work on it, then he probably didn't fix it.

 

But there are various possible sources of oil burning and any one of them could be valid. Jim noted above that rings and valves are the two most common, and as I understand it rings are significantly more expensive than valves. So the question is if the guy announces that the problem was the valves which he fixed, how do I know that the problem wasn't really the rings? Which is besides for verifying that what was claimed to be done was actually done to begin with. (It's possible that you can tell this without taking things apart, but I don't know if this is the case.)

 

Also, one other question, if I might.

If in fact the guy puts in some sort of denser oil and an oil additive and then runs the compression test. Will the test still measure what it is supposed to measure, or will it give me a misleading result? Or would the results still be valid. (The guy notified me yesterday that he intended to have it tested today, but that he had given it an oil change, and would possibly drive it around a bit "to test it out".) It would appear that he intends to have the test done at an independent shop, and I've asked for a copy of the written results, but I want to make sure the test is not being skewed somehow.

 

A real quick and dirty check for excess blowby (ring/piston/cyl wear) is to pull the pcv valve from the valve cover when the engine is idling and also when you rev it (hit the gas pretty hard when you do this). You do not want to see smoke start belching out. Unless this vehicle is an antique, you have a CCV (closed crankcase ventilation) system. No blowby gasses are to escape into the atmosphere (pollution, and it upsets the greenies). So look inside the line leading from somewhere on the engine (typically a valve cover) to the air filter area. It may be downstream from the airfilter; if what you're driving is old it may be on the air filter housing sitting on top of the carb. Hopefully there is no oil in there. If there is, and if it's smoking when you repeat the engine operation conditions noted, then there is sooooooo much blowby that the pcv alone can't draw it all into the intake.

*At 200 miles per quart, there 's just got to be be some blue comming out the tailpipe under certain engine operating conditions.

 

You can bandaid an engine with thick oil or additives. So if this is a reputable shop, ask the guy outright what he did to fix the problem. An oil change ain't going to do it.

If you still suspect that an additive or thick oil was used, you could drive the truck for an hour or two to make sure the engine and oil are fully up to temperature. Just getting it to the warm mark on the engine temp guage doesn't mean everything is up to operating temp, it takes quite awhile.

Once you are sure things are truly hot, run a compression check. The oil or additives should be thinned enough that if they are hiding things, it may show poor compression on one or more cylinders. You could also squirt about a table spoon of thick oil in each cyclinder and then check that for compression. If the compression goes up, then it was the rings. If the compression is still low, it is probably the valve guides. Two low cylinders next to each other usually mean a bad head gasket which could mean oil leakage.

Good Luck,

Jim Henderson

 

The plot thickens. I just got a call from the dealer and he says he had his mechanic (an indepent mechanic but one with whom he does regular business) did a wet/dry compression test and it shows no oil burning at all - engine compression is fine. He is going to give me the write-up from that mechanic.

Now the facts that I know are that I changed the oil myself last Sunday and the next day it was about 0.4 quarts lower and the next day about 0.5 quarts lower. Saw this with my own eyes. Could I be wrong? My mechanic also identified an oil leak in the valve cover gasket (the dealer replaced this) but my mechanic insisted there is no way that amount of oil could be leaking from that source.



I think to be safe I should change the oil tonight to get rid of any possible additives or heavier oil (the dealer claims he used 10W40 and no additives) and then have another compression test done. But this dealer knows I've had a mechanic look at it, and knows I will bring it back to the guy. So I wonder if there's possibly some trick I'm missing?

The whole thing is weird.

 

Hmmm.

Dumb question, but when you added oil during the fill up, how much did you put in? This is dumb but yah never know... When you change oil and filter, the filter will take some oil to fillup. This will make the oil level change a half quart or so depending on whether the filter is dry and it is the first startup and whether the filter is draining back into the pan when it sits over night. I mention this since I don't know your level of knowledge on engines and we have all been in the situation where we were learning and missed a few details. If you are experienced, my apologies, if not then maybe this is your problem, and very easy and free to fix.

When you check oil, it is best to check it in the morning before starting and to top up. Then check it later in the week at first start up. If the oil is burning or dropping then yes there is a problem. If you are checking it at different times, then your level may vary and give you false readings. Try to follow the same routine when checking any fluid since temperature and whether it has been running recently affect levels a lot.

A reputable dealer usually has more to loose by trying to hide something like this. A call to the local Chamber of Commerce or Better Business Bureau can often cause them more headaches than it is worth. I don't think they would try to pull a big trick on something as obvious as oil burning, especially if they said they would make it right.

You said you changed oil last Sunday and next day it was .4 lower, then next day .5 lower. Does this mean you dropped almost 1 quart in two days? If this is the case, then you definitely have a leak or are burning oil. If you are just varying between .4 and .5 low, this is just simple variation depending on situations as described above.

One other trick to try is when you get home after a good drive, put a big sheet of cardboard under the engine. Check it in the morning. Any big leaks should show up unlessit is a leak that only happens when the engine is running and spewing oil on the roads and maybe the underside of the truck.

Good Luck,

Jim Henderson

 

Thank you very much, Jim. No insult taken or needed, frankly - I know how to change the oil but not a whole lot more.

After one day, when the level had gone down 0.4, I agonized over whether it could be just the filter as you suggest, but the next day it went down an additional 0.5. I didn't put down paper, but my driveway didn't show anything.

 

I got the number of the actual mechanic who did the work and called him up. He said the engine compression was normal which rules out piston rings, and that while the spark plugs were in bad shape generally, they did not have oil on them. He says if there is in fact oil burning it would have to be the valve seals. The dealer says he will replace the valve seals if it continues to burn oil but wants some assurance that fixing the gaskets didn't cause the problem. So he'll write me an agreement to fix it if it continues to burn oil.

This sounds good to me, if true. I figure the most I'm risking is a couple of hundred bucks for valve seals. But I'm not sure if this is true.

Thanks again for your help on this.

 

If it is a four-cylinder, valve seals should not be too expensive. That is a more common source of oil burning than worn rings in older cars anyway. If the clearance between valve stem and guide is to great and/or seals have hardened or worn, oil will be drawn into the cylinder on the intake stroke.

A stuck PCV valve also could be the cause, a $5 fix. Look for oil in the trottle body.

Jim