My XJ (Helen) has 215k on it and is starting to use a good bit of oil, I had to add about 3 quarts in between oil changes. As far as I can tell there are no leaks, and I'm not getting any smoke from the exhaust at all. The only smoke that I ever get is from the oil fill cap hole when I open it to add oil. I take it this means that either my piston rings and/or my valves are shot, but I still find it strange that I'm not getting any smoke from the exhaust.

 

In for answer/suggestions. My xj has the same problem. I only drive mine on the weekend and it uses a quart about every tank of gas. no smoke and no leaks. would love to know what is going on.

 

I do drive my XJ pretty hard, I work as a delivery driver 4 nights a week and put about 70-100 miles a night on it (and feel terrible about it). For me it may just be the harsh driving that's making it use that much.

 

For high mileage engines with oil consumption, the best strategy is to perform a compression test.

It's a good "snapshot in time" of the internal condition of the engine. If the engine shows low compression on any cylinder, add an ounce of oil to that cylinder and repeat the test; this is called a wet compression test. You can tell a LOT from a compression test and it is simple to do. Many big box parts stores will rent you the gauge if you don't have access to one.

The compression spec. for the 4.0 is 120-150 psi, with no more than a 30 psi variation between cylinders.

 

lets say he does the compression test and it's low or there is more than 30 psi difference. would that mean there is blow by? and if it is, where is the oil going?

 

x2

I'm just at a loss here....I like to think of myself as fairly mechanically inclined, I do all of my maintenance myself, but once I get into actual mechanics of things I'm lost.

 

bump bump?

 

If the compression test is low, it's likely piston rings. It could also be a valve issue, but that won't necesarily account for oil consumption. Rings will. I can see that if the valves aren't seating properly that oil could get past them. These engines are noted for valve spring issues with worn engines. However, you'd think that there would be performance problems if this was happening. You didn't mention any.

Oil consumption/loss is generally caused by one or more of several issues with worn engines.

1. Bad rings allowing excessive amounts of oil to pass into the combustion chamber.
2. Worn valve seals which allow the same. This doesn't necessarily mean that the valves themselves are bad.
3. Leaks generally with seals and/or gaskets.
4. Bad head gasket allowing oil to travel from the journals to mix with other fluids, often coolant, or the combustion chambers.

You can be burning oil and not see a lot of the blue smoke which is a definate sign of combustion chamber consumption. It may be there, but not to the degree that we occassionally see with some vehicles depending on the severity of the problem, so you don't realize that it is happening. This is more common than you may think. I had an '88 Corolla work beater that used oil but you didn't see a lot of smoke. It definately was burning oil.

Definately do the compression test. That's a good place to start. Also, look at your spark plugs. If you are burning oil, thay may appear blackened at the electrodes, especially where oil is excessively getting into the chambers. As a decent stopgap measure, I'd recommend using Lucas Oil Treatment. It reduced the oil consumption on the Toyota noticeably. Substitute a quart for a quart of oil during an oil change. Ultimately, though, you'll have to get to the root of the problem.

 

Is there any way that oil could be leaking into the transmission? I've noticed my ATF is kind of brown

 

I have this problem, no smoke out of exhaust, no leaks, and good compression.

What I found out was the 4.0 engine used a piston with short skirts and really small rings. While the compression rings hold up OK, the oil rings will allow oil to pass into the combustion chamber. Since all 6 cylinders instead of one or two are burning small amounts of oil, the oil is burnt off and so no smoke and no fouled plugs, plus you've got good compression.

 

So the solution is to replace the piston rings?

 

I'm planning on having my engine rebuilt with different pistons that have fatter rings and longer skirts If your engine isn't smoking or using to much oil you can always just keep adding oil until it gets real bad or you can save up the cash to rebuild it.

 

Really need hard data to know how things are inside of your engine.

Anything less than a compression test is pure guesswork. If you don't want to do this test yourself, any shop is qualified to do this for you and it won't cost you much. Ask for an estimate.

As for your brown ATF fluid, when is the last time it was changed? I recommend dropping the fluid in the pan every 30k (there is a drain plug just like there is on your oil pan) and replacing it with fresh Dex/Merc III compatible fluid. Your fluid should be "red" in color, not brown. Fresh fluid is important to the longevity of your transmission.

 

I did a drain and fill on the ATF when I got the XJ, just haven't had time to drop the pan and do the filter yet

 

The problem with my engine anyway was my compression is good, 135-150, but it was still using oil. The 4.0 liter engines crappy pistons and narrow oil rings was the problem on my engine.
Sometimes you can't get hard data without opening up the engine.