Spark plugs: 7 tan, 1 black

[MacGyver]

As you are already finding there are many possibilities. All you can do is use a logical process of elimination. Be carefull regarding the compression/leakdown test results. You can have good cylinder compression with bad oil rings. In some cases oil in the cylinder can actually raise the compression. You are wise to monitor the oil consumption as a baseline. Oil consumption doesn't always show up as residue at the tailpipe. The vacuum test is also very good advise. The oil on the spark plug threads is a big clue We all have a tendancy to think the worse at first. Start with simple than work you way down the diagnostic tree. You have a major puzzle on your hands that I believe will lead to removing the head. Let us know. You have all of us very curious..

Thanks, Matt

[RICK LAKE]

ceslaw Before you start pulling the motor apart, a couple of ideas on this problem. First off which cylinder is it? Where all the motor parts new? Heads, Block and Intake? if yes go to next idea if not, the milling of the motor block,heads or intake may not all be sitting flat causing the oil to either be pressurize or sucked into a poor sealing area. When you start the motor, does blue smoke come out of the side pipe? If the motor has a lumpy idle the vacuum gauge is not going to help. Are you running a PVC valve on the motor? it may be the wrong one and causing pressure in the motor and pushing oil through a seal. They sell a dye kit for about $70.00 that the dye goes into the oil. You run this for 20-50 miles and then check it with the light and glasses in the kit. It leaves a nice yellow stain and shows you where the leak is coming from. If #4 or #8 are the problem your oil returns may be partially blocked by the gasket, and over filling the valve covers. The Felpro gaskets need to be checked for this. I had to trim both sides to the returns for this problem. The rings are not broken in yet, so 1 quart of oil per 1K of miles is normal. If the engine builder set the ring gaps up wrong this could be a problem. A leak down test and compression test would tell for this. Before I go into more checks start here. If you want to talk call me at 732-254-3536 in the evenings. Good luck Rick L.