This is amazing. I mentioned before that this car uses 2 quarts of oil between 3000 mile oil changes. Maybe the previous owner didn't take care of it.
So it's down about a quart, halfway between oil changes, and I turn a corner and am hearing weird rattling sounds. I accelerate at slow speed and heard them too. This is going on and on and it sounds obnoxious.
So I put a quart of oil in and voila, all the sounds go away.
What the heck is happening to the engine, if I merely let the oil go down by a quart?
The engine is already damaged, and I suspect that there is a fair amount of sludge in the oil pan and valvetrain due to the neglected oil changes that caused the engine damage.
Sludge in the head restricts the flow of oil, so when the engine is a quart down, there is probably even less in the oil pan because oil is pooled in the head where the valvetrain is instead of flowing down and returning to the oil pan. You are burning oil because of problems with the rings that seal the combustion chamber. The neglect that wore the rings probably also wore the crankshaft and connecting rod bearings. Worn bearings reduces oil pressure, and the reduced oil pressure wears the engine even more quickly in a vicious cycle. That cycle has already started in your engine.
The engine is probably on its way out, you can help it along by checking your oil every time you fill the tank and topping it off as needed instead of waiting for it to make noise.
I have a '94 BMW that I observe the Oil Change Interval as defined by the car's computer, which is closer to 10,000 miles than 3,000, and I have not used a full quart of oil and the change interval is just now approaching.
It would not be alarming that you use a quart in 3,000 miles, but it is alarming that you use one in 1,500 miles. That's a quart for every four tanks of gas, perhaps five tanks. But it is more oil than you should be using, and is bad sign.
Probably about three ballparks. In a case like that, the cheapest way is usually a swap with a good engine from a wreck. If that engine is sludged up, I would probably try to slow clean it. It would be better to tear it down and clean it, but I doubt that is too feasible in your case. I think what I would probably do is add ATF instead of oil on the 2nd quart between changes. IE: the quart you add before changing it. But no more than a quart of ATF for the 4 quart system. What that will do is help clean the crud, but not so fast as to plug up drains or the oil pan screen. Hopefully anyway.. Myself, I feel that is safer than doing a full blown engine flush, which can lead to serious problems. And if you did a strong flush, you would want to pull the oil pan to collect all the gunk. It will also thin the oil somewhat and help it flow better through clogged drains, and hopefully eventually clean the drains and passages a bit. If you are paranoid about ATF, Rislone or Marvel Mystery Oil will do the same thing. I've used Rislone for this, and have never had any problems with it. It's pretty safe. If you add two quarts in between changes, you are adding a quart every 1000 miles or so. So that's about how long you would run the cleaner before dumping it and changing the oil.
If you are clogged up so bad as to plug drains possibly, that's also bad enough to clog the oil pan screen. Anyway, it's probably better than doing nothing. If it continues to get worse, it will eventually fry the engine. So I think it's worth trying a "slow" clean using the solvents, and 3000 mile oil changes. The reason I think it would be better to add the solvent on the last quart added before the oil change is the solvent will break down some crud, and it will be time to change the filter, along with the oil. Then use only oil when you change the oil. Add the first quart using oil, then add the second as solvent. Then change the oil again, repeat over and over.. It will slowly clean some of that stuff up.
The ones that think extended oil changes are a good idea would do well to note your predicament. This is precisely what can happen. And it's ugly. :( But.. yours is not totally hopeless yet. If you could get it cleaned out a bit, it would help it last longer. The oil pressure would come up, and you would have flow throughout the engine. It might still burn oil, but at least it would not be prone to seizing up. And that's where you are heading if you don't do something about it.
Normally I don't advocate using anything but oil in the crankcase, but your type of case is one where it's better than doing nothing. BTW, when they change the oil, tell them to run the engine a while and get it hot before draining. That will help suspend and drain more crud.
BTW, I'd use regular filters. Don't use the "micro filtering" jobs which might load up too soon. You want as good a flow as you can get.
There is also the possibility that the cleaning could widen clearances that are presently filled by varnish, etc, but like I say, if the only other option is waiting for it to get worse, and fry, it's probably worth the risk. IE: it could make it smoke worse, if it's smoking now. But.. smoking is better than seizing up due to lack of oil flow or pressure.. :/ BTW, this assumes you are actually sludged up.. The easiest way to tell for sure is to yank the valve cover. You might be able to see a little through the oil fill hole.
I remember back years ago, I guy I worked with used to use kerosene to clean sludged engines. He'd mix about 50/50 oil and kerosene and run it for short periods of time, drain, repeat if needed, then straight oil. It worked pretty well, but you kind of need to know what you are doing, how long to run, etc. I remember in particular an old Pontiac Lemans he had to do that to, which he discovered was filthy while changing some valve train parts.
You can try nm5k's method but if you do, you need to be much more diligent at monitoring oil level, note the part about pulling the oil pan to clean out the crud. The oil pan uses a formed-in-place gasket (basically a special type of caulk) that has to set before running the engine again and is about a 2 hour job.
The reason you need to be much more diligent in monitoring the oil level is that if the rings are worn, the oil-solvent mixture can burn even more quickly than straight oil so your oil consumption can go up.
I remember your question about whether or not the car needs to be on level ground when checking the oil, so here is the proper procedure for checking the oil.
To check the oil:
- park the car on level ground
- put the transmission in park
- set the parking brake
- shut off the engine
- open the hood and pull the engine oil dipstick (with the yellow handle and not the transmission oil dipstick with the orange handle)
- wipe off the engine oil dipstick
- re-insert the engine oil dipstick in the tube all the way
- pull the engine oil dipstick out and note the oil level. The cross-hatched area on the dipstick is 1 quart below the full mark. If the oil doesn't show on the cross-hatched area, it is at least 1 quart low. Add oil until it is at the top of the cross-hatched area.
While you are at it, check the automatic transmission fluid (ATF) level. The transmission dipstick has indicators for when the ATF is hot or cold. If the car has been running for only a minute or two, use the "cold" marks as indicators. The ATF should be red and translucent, not brown-black-muddy color that you can't see through. If the ATF is brown, black, muddy or smells burnt, have it drained and refilled, do not have it flushed unless you want to buy a transmission in 6 months.
Also while you are at it, take a look at the brake fluid level in the brake fluid reservoir mounted on the firewall in front of the driver's seat. It should be between the low and high marks. If it near the low mark, have the brake linings checked. The brake linings should be checked every 5,000 miles when rotating the tires.
Since you've invested 2 or 3 minutes checking the fluid levels so far, invest another 30 seconds and check the power steering fluid level. It has a dipstick built into the bottom of the reservoir cap. If the fluid is low, top if off with ATF. If the fluid is real low, have the steering system checked for leaks.
To answer your question, a ballpark on swapping the engine for a used one is probably around $2,500 for a medium quality job. Figure $7,500 if someone who shouldn't be working on cars does the job because it will have to be done twice, about the same for a brand new engine.
You are replacing half of the oil between 3,000-mile changes. This leads me to suggest that perhaps you can stop changing the oil because it is always fresh anyhow. If you observed a more logical and prudent change cycle of
5,000 miles, or even the recommended 7,500 miles, you would always have fresh oil in the car anyhow, given your reports of how often you add oil. You can save oil and money by replacing the filter only...
I knew somebody who did that, only about every couple hundred miles, but one day he decided to do a regular oil & filter change, and his oil stayed kind of clean looking (transparent) for about 1,000 miles.
When you change the oil, do you put in the amount specified by the owner's manual, or do you fill it until the dipstick reads correctly? Because I've heard of used cars coming with the wrong dipstick or dip tube, and that apparently happened with my friend's transmission because he experienced slippage the first time he changed the fluid and eventually noticed the amount of fluid that drained out was about a quart less than normal. He also noticed the dipstick would sink about 1" too far, so by putting in a quart more than the "proper" level, shifting became normal again.
How's the connection between the oil pickup and pump? Are there any gasket leaks that could suck in air?
Maybe you should take a sample of the used oil and send it to a testing lab (Caterpillar dealers can do it) to see how serious the wear is inside the engine and how many more miles it'll probably last. The test can tell where the wear is happening by what metals are high. It costs about as much as an oil change, but in this case it might make sense. It also might not hurt to install an oil pressure guage to see how the bearings are holding up (10 PSI minimum per 1,000 RPM is considered OK).
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