Re: oil consumption -- update
I did some snooping around and found 3 places I am leaking
1) rear oil return tube (near the exhaust rear of block to head)
3) striped and now missing bolt on rear of oil pan. pretty minor
the exhaust side of the block is fairly well coated with oil, so I am hoping that taking care of these items will significantly reduce my consumption.
Older cars, high miles.., loose clearences
I think we are just suffering from old car / high mileage syndrome. My car has 270k with a new head and still burns a quart every 1500 miles. The plenum is the tell tale sign... full of oil from blow by.
We all just have to live with it until we rebuild the engine.
not sure where the blow by is?
Re: opps.. stupid enter key
Blow-by from combustion pressures past worn piston compression rings pressurizes the crankcase, forcing oil vapors back up through the cylinder head and over to the intake plenum via the breather tube. The crankshaft does a pretty good job of creating an oil cloud that can get carried upwards. There's a drain hose from the plenum back to the sump for most of it. I usually see a bit of oil on the bellows from the AFM to the plenum. I've also seen it on most of my other fuel injected cars.
Our cars don't have a PCV system in the normal sense. The crankcase just vents to the near-atmospheric pressure plenum upstream of the throttles. There isn't a PCV valve in the system. Traditional PCV systems vent to the intake manifold downstream of the throttles where a vacuum exists.
As for clearances, theres no doubt that things open up over time. But our '88 has burned/leaked/? oil at about 1,500 miles per quart since we bought it at 12,000 miles. It's somewhere around 178,000 miles now. I'd like to think that Mobil 1 has something to do with it.