Where is my oil going? Help please.

[fornaroj]

Bought my 1955 two years ago. Has 90k miles, runs great and hums beautifully. Before putting the car away last winter, I noticed that I was using 1 quart of oil every 100 miles. If I was burning it, it would be a real smoker at that rate, but no unusual oil burning from the exhaust. I have the usual oil spots when parked. Brought the car out last week, changed the oil and was down a quart after a 75 mile trip. I had someone follow me to see if there was excess smoking, but nothing unusual. The coolant is fine. Is it possible to have a leak that would occur only when I am driving? Could use some advice.

 

[paul2748]

Have you run the car while in the garage (or outside) for a fairly long time with something under it to see if its leaking.

While they leak when not running, they will push more with pressure. It would seem that with that amount of usage you surely will see big spots on the ground (driveway).

 

[fornaroj]

Thanks. I have had it idle in the street, but not for a long time. I will give that a shot. When I pull away from the curb, I do see some small drops on the street.

I had the valve seals changed before the Winter but nothing changed. Do you agree that if the car was burning that much oil at that rate that it would look like a smokestack?

 

[paul2748]

With that kind of consumption, if it was going into the cylinders it would smoke something terrible I would think. If the car runs good, then oil is not fouling the spark plugs. Might take a look at the plugs to see if there is oil fouling.

Thanks. I have had it idle in the street, but not for a long time. I will give that a shot. When I pull away from the curb, I do see some small drops on the street.

I had the valve seals changed before the Winter but nothing changed. Do you agree that if the car was burning that much oil at that rate that it would look like a smokestack?

 

[fornaroj]

Good point. I Will check the plugs. I changed them last year. The old ones had carbon on them, but no oil. I will check them this weekend.

 

[fornaroj]

I now have a partial answer to my dilemma. I spoke to an engine re-builder who mentioned that I should put a quart of Marvel Mystery Oil in the crankcase and run it for about 100 miles before changing the oil. It would clean out any sludge, particularly on the rings. I did that and let it sit for a few days. Found three (pretty heavy) leaks underneath the car (probably due to the thinness of the oil additive). Leaks appeared at the oil pump and rear seal. I also switched to a heavier oil (Shell Rotella 15W-40 as indicated on several TBird forums).

My conclusion is that I am, in fact, dripping when parked and likely when I am driving. I am going to look at the leaks and fix what I can. I will live with it for a few more years and overhaul the engine in a few years.

I appreciate your help.