Fellow vanagon types 
Oil pressure is influenced by lots of things the viscosity and temperature of the oil the clearances of the rod and main bearings to the crankshaft journals the fit of the oil pump to the case and the thickness of the gasket between the pump and the pump cover. One of the oil pressure problems people have experienced when they buy a rebuilt or reassembled engine is with the new aftermarket oil pumps.  These new pumps don't fit as tight in the case and the pressure loss at oil pump bore in the case and the pump body can be significant. All WBX gasket sets I have seen include a gasket for the pump cover that measures .006ths. The part number for these gaskets is the same as the old bug gaskets those have always measured .004ths.that extra 002ths can cost allot of oil pressure when the oil is hot.  I now use selected used pump in my rebuilds because they have better oil pressure cold and hot than the new aftermarket oil pumps. I also use the thinner pump cover gaskets. The waterboxer engine as we all know have hydraulic lifters and the hydraulic lifter engines VW has made are designed to have less than 10 pds at idle this includes the in line 4 cylinder golf jetta engines. To much pressure at idle can prevent the lifter from self adjusting but I don't feel that this is a part of the problem WBX engine have with lifters when the stock pump is used. The other thing that is often forgotten is that the fresh engine needs a thinner oil for a short time to let the rings brake in and this thinner oil does make less pressure. 
The 1.9 engine has oil pressure problems that are different than the 2.1 engine.  When the 1.9 engine is reassembled without alignboring the case the main bearings do not have the proper crush. The 1.9 main bearing bore become larger to the point that the main bearings are moving in the bore replacing the bearings does not solve the problem. I have an article on this that has yet to be posted to my web site P mail me if you would like me to forward a copy of this to you.   
I understand the idea that more is better but more is not better when you don't have a problem to begin with. lets not fix it if its not broken
 
going faster miles an hour 
I remain
Bob Donalds 
http://www.bostonengine.com
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