Stu & Alan,
My first suspicion is that the oil seals on the valves (especially on
the intakes) are either missing, wrong, or incorrectly installed, and/or
valve guides are worn. This would account for oil-fouling of plugs but good
compression.
At 3,000 miles, your rings SHOULD be seated, but it's possible that the
oil- control (scraper ring) is not, or was installed incorrectly. (Since the
scraper ring has little effect on compression, problems with it won't be
revealed by a compression test or leak-down test.)
What type & viscocity was used during the break-in? What type &
viscosity of oil is being used now? Both of these can have a significant
efffect on oil consumption. BTW, a quart in 500 miles sounds somewhat high,
but not outright excessive for an XPAG engine.
Reducing oil pressure will NOT improve the situation!!!!! There is no
path by which oil that is under PRESSURE can get into the combustion
chambers. (Once the oil exits the bearings & bushings, it is no longer
pressurized..)
Hope this helps
Carl Fritz
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