Where is the oil going?
 

The engine in my car consumes about a quart of oil every 500 miles or so. I have owned the car for a few years and just added oil when necessary without paying much attention to how often or how much, until recently.

There is no smoking from the exhaust on cold start-up or on deceleration/acceleration, no oil accumulating in the intake manifold or the base of the air cleaner. I do have a closed PCV system with an adjustable Wagner PCV valve that is tuned for the engine and the valve covers are well baffled. No external leaks exist.

I replaced the intake manifold gaskets about two years ago as a result of a coolant leak above cylinder No. 1 and used the FelPro S3 gaskets and thread sealer on the manifold bolts, so all is well there.

I did a compression test some time ago and all cylinders are within 2-3 PSI of each other. I recently did a cold leak down test; results are 4 cylinders at 7%, 2 cylinders at 6% and 2 cylinders at 4%.

I recently replaced the valve stem seals even though the engine didn't exhibit any symptoms of worn seals but, it is an easy enough job.

The spark plugs are clean with no oil or unusual deposits.

Oil pressure is 75 PSI cold, 62 PSI hot cruise and 32 at hot idle.

The engine is a Ford sportsman block based 302 stroked to 331with 18,000 miles on it. Oil consumption aside the engine is a very strong runner.

what kind of oil?

Dwight

Royal Purple 10w30.

synthetic motor oil?

Dwight

Yes, synthetic motor oil.

All engines consume oil between servicing, fact of life.

If yours has no external leaks, it has to be burning it.

500 miles at say 10MPG is 50 gallons of fuel.

1 quart mixed with 50 gallons would go unnoticed out the exhaust.

The oil gets consumed through the inlet guide, the exhaust guide if the exhaust system works too good, and past the ring pack.

The oil is also suspended in the crankcase air and consumed via the pcv system.

I would have a look at the hose between the PCV valve and the carburettor.

Maybe you need to incorporate an air/oil separator tank.

I had the same problem with a 347. Change to dinosaur oil and I think you oil consumption will go away.

Dwight

Dwight....switching to dino oil was suggested by a local engine builder also, I'll try it at the next service interval.

Gary....the hose from the PCV to the carburetor is in new condition and I'm aware of how engines work but, a quart in 500 miles seems excessive, even for a performance engine. I've given some thought to an oil separator as well.

My daily driver is a 2010 Mustang, supercharged, and the engine doesn't consume any oil between service intervals. Maybe comparing apples to oranges though.

Ken

Since you've eliminated most of the major players, and since your engine doesn't smoke and the plugs look fine, it's probably just a characteristic of your particular engine. I wouldn't lose any sleep over it.

From what I've heard, many new car manufacturers won't even consider a quart of oil every 500 miles as being unusual. And that's Toyota, BMW, and Mercedes.

In past years, the manufacturers would generally consider anything more than 1 qt/1000 mi to be an issue. These days tolerances are better. My daily driver, which is a BMW twin turbo with 113k miles, uses about a half quart per 7,500 miles. My other daily driver, a Chevy Truck, uses the same or less. I think 1 qt/500 mi is a lot and I would try to identify the issue.

What's cheaper, oil or an engine overhaul? Ditch the PCV for 500 miles and see where you are maybe, but if the smoke and puddles don't embarrass you, it's not burning or leaking enough to worry about.

Mine uses about 1 quart to 700 miles...more with more time at redline. Consider it a continuous oil change.

I'd try this first,switch to any name brand 10/30 or 15/40 dino oil and see what happens.......

I have a buddy that farms and has been using one particular type/weight of engine oil in his equipment for years, no problems....some time back a salesman from a competing oil company paid him a visit and gave him enough free oil for an oil change in a couple of tractors hoping to get his business...he tried the competitors oil and found his tractors would "use" about a quart of oil every 5 hours of run time whereas they would use about a quart of oil every 20 hours of run time with the other oil........needless to say, he didn't switch oils......

Some engines are funny that way....

David