OK need some recommendations. I have a 79 F250 Camper Special 4x2, with a 460/C6 combo. The truck has a total of 146,000 miles on it and it is all stock. My issue is I am now adding a quart of oil every 200 miles! It smokes very, very little, and does not leak a drop. It also does not smoke at start up. Does anyone have a sugestion on what it may be? Rings? Valve Seals? Curious if 460s from this era had any common problems with this issue. Thanks for the help guys!

 

My 302 uses over a quart in 100 miles LOL. Runs great though, but I'm looking at doing a new motor soon. Sorry this doesn't answer your question but I wish I could go 200 miles before having to check my oil LOL

 

Just a wild guess.
It could be an intake gasket leak drawing oil from the lifter area.
Ive' only seen this one time on a chebby, don't know about a 460 though.
Ran great, no smoke, about one quart per 200 miles or less.

 

Wouldn't it idle really rough if there was that much of a vacuum leak? Mine idles fairly well.

 

460's are usually pretty damn good, my original bore and piston 1969 429(similar but different pistons and crank), which has been crashed in the original Torino it was in, sold to pay for fines(lol) then sold to a mud bogger, and seen many runs on nitrous-about 3 years-and seen some hell. Now it has a broken piston skirt on #8 from revs, and run on propane since 1998 and doesn't use oil. I run 10w30 in it and rarely have had to worry about oil consumption.
However, I did have a 76 F150 w. a 460 2wd, which nearly used as much oil as it did gas... Had to clean the plugs every 2nd week or it would miss. Mind you when I bought it, it had no air filter, or thermostat.
So, good and bad. Although-I would check your dipstick vrs. amount of oil-when a fresh oil change is done-might have too much oil in it. I ran too much oil in my 429, it leaked at the main seals and used oil-now that I have the matching oil pan and dipstick she don't really use any oil.
Has this engine seen much operating time lately? Longer trips, many thermostat cycles and heat to burn off crap in the oil, vrs. short trips, barely gets warm?(fuel prices)

Otherwise, time to do a good compression test of all cylinders to compare each hole, and leak down test (best out of 100%) of individual cylinders to see where there are problems. Not the easiest for most.
If the engine seems worn, try some 10w40, or even 15w40(high detergent) oil with something like lucas oil treatment.
There are many more things to try or test, but it compounds in ways... heh
Good Luck!

 

Don't make the same mistake I did. Mine was using oil the same as yours. I tore it down and did a rebuild. Every thing was perfect in the engine. The rings were like new even after a 140k. I had to break the rings when I took the off of the pistons so that I wouldn't get them confused with the new set. Everything else was the same way. The bearings, wrist pins, mains, Camshaft bearings.etc. the only thing wrong with the engine was the valve seals. They had hardened over the years and broke apart. All of the oil was going down through the intake valves.

It only takes a couple of hours to change out those darn seals and I spent weeks and a lot of dough rebuilding that engine when I could have cured the oil consumption problem in a couple of hours.

 

A compression test is the only thing that will tell you what you want to know. You're just messing with your head otherwise.

 

Thanks for the help guys. I had heard about a trick to do a compression test; then squirt some 30W in the cylinder and di it again. This way if the compression went up due to the oil it meant you had an issue with your rings. If the compression stayed the same you had an issue with the valves since the added oil would have no effect. Anyone ever heard if this truly works?

 

Yes that oil trick does work, test the cylinder then squirt the oil in and test right away. I do have to admitt I can't imagine losing that much oil without any exhaust smoke.

 

My 460 used about a quart every 500 miles except when towing. Then it would go down to 200 miles per quart and I never noticed any smoke either. I know it is hard to believe, but maybe the 460 burns it so efficiently that the smoke isn't noticeable. Mine would only put out a slight whiff of blue smoke occasionally.

 

100% true.

Important: is your PCV system in good shape? All hoses connected, PCV valve functional, fresh breather filter. A poor PCV system can often be linked to oil consumption. I don't know about a full quart every 200 miles, but you should check it anyways.

 

A 460 uses a valley pan, so not likely.

It's easy to check the PCV system, so I'd do that first. Then a leakdown test, or a compression test if you can't do a leakdown. Neither one of these will show worn out stem seals, though. But if your rings and valves are tight, and your PCV is kosher, then stem seals would be the next thing to look at.

I'd first check to see if your crankcase breather hose has enough vacuum to hold up a business card. If it doesn't, you have blow-by or PCV issues.

 

Sorry this doesn't really help, but I couldn't resist. WHen I got my 77, it ran like a top, but during the 160 mile trip home, it burned 3 GALLONS of oil. Yea-i had to stop about every 20-30 minutes and put a couple quarts in. Needles to say, that motor is no longer in the truck.

 

I have a '97 F-250 with a 460 in it. It, too is using a quart every 150 miles. No smoke, even I start it in the morning. I can't figure this one out. A friend said something about an oil bypass...anyway have you figured out your problem?