Yow! Using Oil!

Hi all--

Lately, my 66 has been using oil--about a quart every 2000 or so. Before this summer, it was tight except for some minor seeps.

On my way to a show in Biloxi, I had some extended highway time at about 75 mph for almost 2 hours. (The car is mostly an around town machine with occasional pleasure drives in the country.) When I got back from MS, the car was down about 1.5 quarts. I panicked and started keeping records--usually 2-3 times weekly- of my oil levels.

I've noticed that when the car is used around town, the oil use is almost nil. When it is on the highway, even at a steady speed of no more than 70, the oil use goes way up. Case in point. I put about 100 miles on the car today in the country and back on interstate and my oil level was down 1/4 of a quart. That's not good. Yet, at about 100 in town miles, the oil level holds steady or drops just a smidge.

There aren't any leaks that show up in my catch pans under the car or in the same parking place I always park in, so I assume it is using.

Ideas?

What can I do/have done to narrow the problem, short of tearing down the engine (which may have to be done.)

The engine was rebuilt about 19 years ago, but for about 10 of those years, it was an occasional driver. The rest of the time, it is a daily.

What puzzles me is the incresed usage at higher speeds. What could cause that? Cracked ring? Would a compression test show that?

I'm usually clueless, but I'm really stumped now. Can you give me some ideas?

Thanks!

--Paul

PS I'm running Havoline 10/40, if that makes a difference. Oil pressure is good, but drops a tad with the heat and the AC on.

How does one diagnose a leaking ring or valve seal/guide short of tearing down the engine? (Or invoking your Superman-like power of X-Ray Vision?)

Oz--Thanks. I don't want to sound like a total idiot when I take it in to be checked. This is beyond my skills. . . .

--P

Max Power said:

While putting around town, quite often fuel wash from the cylinder walls will make its way into the crankcase, masking oil consumption and replacing burnt oil with gas. Then when you go for extended highway trips, the heat generated in the crankcase makes the gas in the oil evaporate or burn off, making it seem like you are only using oil on freeway trips. Quite often, you are using oil at a steady rate and it is being hidden by your driving habits.

Using a quart every 2000 miles is nothing to worry about, and even new cars won't get any engine work warrantied at any consumption of a quart over 1000 miles. When I worked at GM dealers 20 years ago, the use rate had to be a quart in under 750 miles before the factory would pay for it.

At any rate, if oil isn't fouling your plugs or smoking out the tailpipe, why spend a couple grand just to save a quart here and there. Many new engines use oil at a rate faster than that anyway.

My opinion is that you would be flushing your money away. Send me the 2 grand and I will send you a quart of oil whenever you need one!

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It isn't smoking or fouling. It just bothers me as it, at least seemed to be, all of a sudden. Still, I guess after 19 years, it is bound to use/leak/seep a bit of oil.

Will 2 grand get that oil overnighted to me and will I get my choice of weight and brand?

Max--

I appreciate the fact that you have my best interest at heart!



--P

Ozsum2 said:

No not really. Comp checks are done by removing the plugs and recording the pressure held by each cylinder. If they leak down or are greatly different than one another, you have a ring problem or valve seat problem. Vacumm checks are done with the engine running and at operating temp. The needle on the vac gauge tells you what is wrong by the way it is moving. A steady needle means all is well.

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OZ--That doesn't sound too bad. Where does one get the set up for a comp check? I'm all for buying more tools . . . .

--P

Where would I test the vacuum--off the carb to the dizzy? Off of the dizzy?