Interesting thread.
Heres an interesting for you experts.
My '85 E350 6.9 cargo van, high miles yes, but I had the heads off for head gaskets last year, cylinders looked nice, didn't look new that's for sure, but pretty good for over 400k miles.
Heres the kicker to this van. It burns about a quart of oil every 150-200 miles.
Stupid me, didn't change the valve seals when I had the heads off, so I taught it was burning all that oil because of that, but bad valve seals would cause blue smoke on cold start right?
Cold start, all it does is shoot a small puff of black smoke. That's it. No smoke at all otherwise. Some black smoke under heavy accel.
But every now and then, and this is when my oil goes down really quickly, is just driving along, all of a sudden, it'll start POURING blue smoke out the tailpipe, it'll stink up the inside of the van with the smell of burnt oil, it will even coat the inside of the tailpipe with oil.... and when this happens, it'll smoke non stop for either 5 min, or 20-25min. Also, looks like it's consistent with 1 cylinder, it usually does this when driving on the highway, so rpm's are very high, makes it abit harder to tell, but it puffs out really quickly, witch makes it look like 1cyl is causing it.
Sometimes it happens just before getting on the highway from my house, 2 miles, it'll start doing it, then I let off the gas for a red light, and the engine deaccels, and stops doing it.
Any ideas? Does it sound like a broken ring? Or maybe a sticky ring?? I find it really weird it does this like it does.
The engine has no blow by to speak of either!
Also tryed 3 different CDR's, the 3rd one being a brand new one, and made 0 difference in oil consumption.