excessive oil use

PCV valve changed lately?

Yes, it has a new PCV valve.

No smoke on start-up means stem-seals are OK. The smoke on accelerating hard is due to extra heat burning oil-impregnated carbon in the combustion chambers.

At a guess the piston-rings are "oil-pumping" due increased clearances in their grooves. A move to an oil viscosity one grade up may make a significant difference.

Jason

Check auto-rx.com

Check auto-rx.com

The idea is that piston rings can accumulate carbon and stick slightly in the lands, thus failing to exercise sufficient tension against the cylinder walls to control oil burning. The oil control ring needs to leave a very light film of oil on the cylinder wall to provide lubrication without leaving enough to burn excessively. With the engine turning at 2,500 rpm (for example), the pistons move up and down a lot, so a very small difference in oil passing the rings can show up noticeably.

I used the auto-rx product. Not sure it made any difference as my engine was already clean, but it will not cause harm and may well be of assistance in your case. (I found it interesting that the development originated in effectively cleaning ink from commercial printing presses)

I had, however, changed the oil much more frequently when first acquiring the car, just to generally clean it out. Later, when I pulled the oil pan to replace the seal, it was quite clean inside. Also, when checking valve adjustment and replacing cover gasket, the valve area is clean. There's quite a bit of heat in the combustion area, and conventional oil can "break down" from heat, leave a residue of gritty carbon which can accumulate around the rings, hence the original suggestion above - plus if it helps, is much more cost effective than any engine work involving disassembly.

Dry compression 195, 190, 195, 200 Wet compression all were 220 New PCV valve, took off valve cover - clean as a whistle, no blockage in hoses

Sticking rings also cause a significant increase in piston "blow-by", as well as oil-comsumption for the reasons you have posted.

To test for blow-by, allow the engine to come up to normal operating temperature. At idle, the PCV valve does not allow too much crankcase scavenging, as this would cause idle mixture problems, but even so during this test, the PCV valve needs to be removed and the end of it covered with sufficient rag to allow some airflow. Once this is done, the hole in the cam-cover is plugged with rag, and the other vent hose running from the cam-cover to the throttle-body is disconnected from the throttle-body. The hole in the TB can be left open during this test. Start the engine and note how much fumes are flowing out of the vent hose. These are all the blow-by fumes the engine is generating. If you can see a continous flow with the eye, then the rings are either worn or have lost tension or are stuck in the piston grooves or worse may also be broken.

If the BB is hard to see, gun the motor to about 3000 revs for an instant and look for any increase in BB. If it remains light,..then the rings are OK.

As a compaison, a really stuffed engine will produce so much BB the smell is unmistakeable. A sort of sweet oil-petrol smell.

Jason