A couple of things I'd like to point out:

1. Lifters are in the "oil path," they need oil pressure to operate properly (this is one of the reasons for the chronic "going flat" problem), and the oil continues on through the lifter up the push rod and into the heads to lubricate the valve train. So, if the bores are worn oil pressure can be low. It's a rare problem, but possible in an abused or poorly maintained engine.

2. Put the biggest oil pump in you can get--I have one made by Melling that works great.

3. Run 20w 50 in anything but a climate or season where is is constantly below 10 degrees, and then run 15w 40. The light weight multi viscosity oils were designed only to improve fuel economy as mandated by the feds back in the '80s. In the case of the WBX engine they can be detrimental because they are physically thinner and won't provide adequate oil pressure in a worn engine. The additives supposedly boost the lubrication effectiveness up to the higher number, but they remain thin, not what you want in a WBX. You can even run straight 30w or up to 50w if you are cruising the desert southwest on a regular basis in the summer in temps above 80, and your engine will thank you for it. I run 30w as a break in oil in all my new engines for the first 5000 miles because of its higher viscosity.

You might as well run this engine for a while, you might get well over 100k out of it!

Stuart