Where is the oil going?

On Fri, 05 Dec 2003 05:59:59 +0000, McQualude rearranged some electrons to form:

How many miles do you get between quarts?

I think you are burning it and your mechanic's are wrong. Did they provide you the specs on the emissions tests? Saying you go a month and add a quart means nothing. Maybe you only drive three miles a day or maybe you drive cross country. The truck could be burning a quart in 3-400 miles and run very well for a hell of a long time. If it's not using more then a quart in 600 miles Ford will tell customers that's normal.

It's inconsistant. Sometimes it will go a few hundred miles and need a quart, sometimes it will go a thousand miles before it needs a quart.

Makes it sound like a leak, except for the total lack of any evidence of a leak.

Yes, but I'm no expert. They explained what ideal for the truck was and then showed me the results, the results looked excellent.

It doesn't use oil consistantly, it might use a quart in 300 miles or it might use a quart in a 1,000 miles; which is why I thought it was leaking but there is no evidence of a leak.

One mechanic suggested that it may only be leaking while in motion, but we couldn't find evidence on the underside of oil streaks.

That's what other's have said. It might be fine but it's also more expensive buying all that oil.

I had a 92 Explorer with the 4.0 engine. It consistently used oil, but in inconsistent quantities, just like yours is doing. Don't worry about, just pour some in once in awhile. It's normal.

JH

With a higher mileage engine, try a 10W-40 dino. Or take your chances w/ 20W-50.

JR

I agree with Joe above. It sounds like its going through the exhaust and burning up in there. My '89 240SX did the same thing before I got rid of it. If it slips past the rings, it means they're shot, and that would explain the oil going down, because it's burning up in the exhaust. Do you notice a cloud of blue smoke when you accelerate? If you do, thats the oil burning up. It could also be something like a rear main leak, because the rear main just leaks onto the other parts down in the engine compartment, not always on the ground and its not always easy to see.

Anyways, pay attention to your exhaust. Guaranteed thats where its going.

And that's why engine manufacturers get away with it. Because people like you accept it. OIL CONSUMPTION IS _NOT_ NORMAL. If it were, then people wouldn't ask about it.

Why wouldn't you start out on the full mark? If you put in the specified amount of oil after a change of oil and filter, then it should be on the full mark. If not, then you adjust the dipstick as needed till it is. Granted there are many that don't end up on full, but this minor adjustment only takes five minutes. Then there's no question as to where it should be.

I remember the 360, I figured Ford forgot to put piston rings and valve guides in those engines when they were built, as I had never imagined any engine could burn oil _that_ fast. Fortunately, 390's were still plentiful and cheap in those days, so chucking the 360 in the garbage to make room under the hood for a 390 was an easy and intelligent choice to make. It seems that the 360 had bottom-end wear problems that allowed oil pressure to escape at the crank bearings, resulting in oil starvation of the valve train. This quickly wore out the valve guides, which then fed a steady supply of oil to the cylinders. In the early stages you won't see too much smoke in the mirror while driving, but it gets worse quite fast as the guides wear out some more. This condition is eventually exposed by a puff of blue smoke when the engine is first started up, due to oil running down the valve stem and collecting at the valve seat of a closed valve, or on top of the piston of an open valve when the engine isn't running. Unfortunately, by the time this tell-tale puff of blue smoke appears at startup, the damage has already been done.

Cheers

-- Sent to you by Ken at kenwho?@sympatico.ca Replace "who?" with "b2" to reply by e-mail

I once had a 73 Pinto wagon that had a similar problem. The valve seals on the 2000 engine were leather. They were good until about 40,000. Some folks knurled them and got another 20,000 or so out of them. I just replaced them and ran the motor another 70,000. It would have gone longer but the rest of the car just sort of fell apart and there was no stopping it.

Some level of oil consumption is normal. All piston engines consume oil Some don't appear to because some blow-by accumulates in the sump and replaces the oil consumed. Here is my opinion on oil consumption (mostly from a previous post) -

All engines consume oil. I think everyone can agree that even the best oil control rings in the world must leave a thin coating of oil on the cylinder walls. They have to or they would not be lubricated. Likewise the compression rings would be running dry and would quickly wear out. How thin do you think this layer would be? Maybe .0000003"? This is really thin, a single oil molecule is most likely around 0.0000003" in diameter. A 4.6L Expedition has a 3.55" bore and a 3.54" stroke. This means that there is a cylinder wall surface area of 3.55" x 3.1412 x

3.54" x 8 = 316 sq. in. The total volume of oil needed to cover this area is perhaps 0.0001 cubic inches. I think everyone can agree that at least some of this oil is vaporized and consumed on the power stroke. For simplicity, we will assume that one half is consumed on the power stroke and none is lost on the exhaust, intake and compression strokes (this seems like a really conservative assumption to me). So, this means that around one forth of the oil coating the cylinder walls is consumed for each revolution of the crankshaft, or around 0.000025 cubic inches per engine revolution. To simplify things further, assume we only drive around in the top gear and never let the car just idle (again, a conservative assumption). For every mile, the engine will turn over around 1625 times. So for each mile the engine should consume around 1625 x 0.00004 cubic inches of oil. This is .04 cubic inches of oil. In 1000 miles, this is 40 cubic inches of oil. 40 cubic inches of oil is roughly 2/3 quart!

So you say - BS! Lots of engines don't use as much as 1/2 quarts of oil in three thousand miles. I agree, so where did I go wrong? Maybe the thickness of oil film is too thick. Cut it in half, so now you only use

1/3 quarts in 1000 miles (oil molecules aren't this thin by the way). Maybe only 10% of the oil is consumed (not 25% as I assumed), so now you only use 1/8 of a quart in 1,000 miles. No matter how you cut it, your engine is burring oil. And this doesn't include oil lost when you are idling (particularly when the engine is cold), or oil lost down valve seals, or though the crankshaft seals, or through leaky gaskets, or by evaporation, or through the PCV system (look in the PCV valve and lines somethimes...there is oil in there on its way to the intake to be consumed).

The inescapable conclusion is that all engines consume oil. Some don't appear to consume oil because combustion products escape past the compression rings and some contaminants condense in the crankcase. This "stuff" can really make figuring oil consumption difficult. If you do a lot of stop and go driving this "stuff" accumulates in the crankcase because you never really get it hot. Then one day you take a long road trip. Your "oil" gets really hot and a lot of the "stuff" evaporates and is sucked into the PCV system and burned. Now all of a sudden it looks like you used a lot of oil in a short period of time.

It might be that using a 1/2 quart of oil per 1,000 miles indicates you have poor oil control rings (or a leak), or it might be that you have compression rings that are sealing really well and not letting a lot of blow by "stuff" into your oil pan.

Just remember, all engines consume some oil. Those that seem like they aren't consuming oil are just making up the burned oil with "stuff".

References:

Regards,

Ed White

Cool! :) Mine only got to the "puff of smoke at start up" stage at 148K miles, never left a trail of smoke, so... the mystery "where's the oil going?".

With the high quality re-build and a CompCam "economy cam" and edelbrock chain and sprockets it runs better than it did when it was new, with more power and a little better gas mileage both. (I have records on the mileage)

And the valves that were taken out of it looked like "licorice tootsie roll pops". :) Yummm

Alvin in AZ

Heh, I almost laughed when I read that, as I have a very similar story from the 360 in my used 75 F100. I suspected the engine was toast when I first bought it due to a smoke problem, but the body was in amazing shape and the price was just perfect. Anyhow, the valves started making a racket after about a week of short distance driving, and checking the oil revealed that it had consumed almost two quarts of oil already. When I pulled the valve covers off, something about the push rods didn't look quite right, so I pulled off a rocker shaft for a closer look. The once spherical ends of the pushrods had been worn into acorn shapes of various sizes, and I was surprised the valves were opening at all considering how much was missing off the ends of the rods. I just replaced them with a set of used ones I got from a mechanic friend, replaced the valve covers and set off to find me a new engine! I found a 390 for it within a few weeks, and that was a good thing. In the meantime the 360 was now going through at least a quart an hour on the highway, and it was costing me almost as much for oil as it was for gas. To save a few bucks, I ended up running it's last days on some "Good ol' 30 Weight" industrial oil I found in a 45 gallon drum at work. Yup, it would have been interesting to do an autopsy on that engine to see what other ugly surprises were waiting inside.

Cheers

-- Sent to you by Ken at kenwho?@sympatico.ca Replace "who?" with "b2" to reply by e-mail

Sometimes in an older ford engine, the oil returnes get partialy clogged and the oil doesn't return to the pan fast enough at certain speeds. Which means that it pools in the cylinder heads deep enough to seep by worn valve seals and be burned. Depending on the type of driving you do each month, this could explain the inconsisdency in oil consumption. Try removing the valve covers and running a coathanger down the oil returns to clean them out a bit. This can also be seen if you have a couple bad valve seals and you first start your engine after it has sat for a while ... the oil in takes a couple minutes to get back to the pan but in the meantime has a chance to seep past the seals, so when you first start it up you get a puff of smoke. :o) Rex