1970 Ford F250 - Half quart of oil per day

I have a 67 Ford F250 with a 352 using a quart of oil every 2 days or so.
I’ve changed the valve cover gaskets, intake manifold gaskets, rear main seal, oil pan gasket and it doesn’t smoke. There’s a little drip under the rear of the engine in between the engine and transmission but I don’t see much on the ground when it sits. Wondering where it’s going

Try parking over a clean piece of cardboard and see if you see more oil spots.
My other thought would be valve guides, that would produce smoke on start up but burn off as the truck warms up.

If this has a pcv valve check to see if it rattles and the hose is clear. A clogged pcv can blow a lot of oil out the rear main seal.

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Thank you guys! I’ll check all that.

Have you considered that maybe it’s burning oil past the rings or valve seals IF the PCV is ok?

Double check it isn’t going into the cooling system as well. Notice anything unusual looking at the top of the coolant in the radiator, or under the radiator fill cap? Under the oil fill cap? If it is an external leak there should be a great deal of oily sludge somewhere on the outside of the engine. If all else fails and you are certain it isn’t just worn/stuck piston rings, and you see no big cloud of smoke out the exhaust on start-up, you’ll have to clean all the gunk off the engine, then monitor where the gunk starts to appear again. There is a dye kit available at most auto parts store, add the dye to the oil, then you use w/a UV light source when examining the engine, that makes seeing the leak easier.

My guess is the problem is as mentioned above, incontinent valve guide seals.

Also check the oil pressure sensor because they can leak a lot.

I’m trying to remember… didn’t the 67 still have the open air breather filler cap? I remember those could get plugged.

The big block sometimes had a problem with the seal (rear valley cover seal?) at the back of the intake manifold.

The all time favorite leak was the rear oil seal on the crank. Those are easy enough to replace. I have seen them leak after a repair and do again and the mech who installed the valley cover let the gasket slip on my dad’s T-bird… had to do it again.

My friend, Tim, had a mom who was a fanatic about a single drop of oil. He was going thru a quart between 3K oil changes, and there were only a few drips on the cardboard. His was the rear main seal.

We used only Ford parts in the 60’s, especially for the rear main. Some aftermarket were slightly smaller diameter.

Just had these gaskets and seal replaced 5 to 6 months ago, rear main seal, valve cover gaskets, manifold gasket, new pcv valve and cleaned the oil cap breather. No oil residue above the rear main that I can see after pressure washing. No smoke at start up or while driving. I think the new rear main seal might be leaking again after being put in 5 months ago.

Thanks for all your input!


Considering the age of the truck I wonder if the rear crank journal was inspected for signs of a wear groove from the rear main seal. If not, and a wear groove is present then installing a new rear seal can easily be a waste of time. This is why stainless steel repair sleeves are offered.

Considering the number of gaskets/seals and labor involved in all of this I will say that if the truck was mine I would run a dry and wet comrpession test just to make sure that engine is worth it all.

At about that period Ford used an oil cap with a rubber hose attached which was connected to the air filter housing as the primary crankcase ventilation route. If that cap was replaced with a non vented cap, and often they were, the result was just what is occurring with this truck. I have bought 2 old Ford trucks that were blowing the dipsticks out of the tubes and burning a quart of oil on a tank of gasoline and after properly connecting a vented cap the oil consumption dropped to an acceptable level. On the other hand I have bought a few that were beyond helping with that repair.

I really appreciate your inputs and will try them.

This was a one owner truck from Montana with 84,000 original miles on it 2 years ago when I bought it, now it has 100,000 on it.

It’s a nice F250 4x4 Highboy

really clean for an old farm truck.

I’ll probably take the engine out and rebuild it, I noticed the main bearings are showing a lot of wear last I had the pan off.

If you’ve owned it 2 years and it ran well until lately it’s unlikely to be some peculiar, incidental problem that is easily corrected. But rebuilding it might not be too expensive or difficult if you have a large shop area and the tools you need. I’ve rebuilt a lot of Ford V-8s dating back to the early 60s but never a 352 but it’s just another piece of basic Ford iron and the sooner you get in there the better. If a piston is galling the cylinder catching it before it requires 1 or more sleeves would be good. And it would make for a much more dependable work truck with a new clutch, water pump and fuel pump and a kit in the carburetor.

That would make sense. Even when the truck was fairly new, by 100K miles the engine was tired.

100,000 highway miles should be just a good start for that engine @mperry_153483. But 100,000 miles of farm work on the other hand could be brutal.

Add a can of Restore to the engine oil.


If the oil consumption slows down or stops, guess what?