What are you using ?

Amsoil has a wide variety of synthetic, high zinc oils to choose from. Personally I use their Dominator 5w-20, but I probably have tighter clearances. I honestly forgot what my hot, idle pressure is, but I get a max about 70 the lights. I've seen idle increases when switching from conventional break-in oils of 15w-40 and straight 30w or 40w to the 5w-20 Amsoil synthetic! Amsoil now has their own break-in oil, but I haven't tried it yet.

Personally, I think 20w-50 is a bit much and would try of 10w-30 or 15w-40. But today even diesel oils have less zinc than they use to to varying degrees so you can't take that for granted. The higher zinc content oils tend to advertise the fact, but do some research.

As Bob S. suggested, stick with conventional oil untill the engine is well broken-in.

High zinc Amsoil synthetics & zinc technical service bulletin:

[ame]http://www.amsoil.com/techservicesbulletin/motoroil/tsb%20mo-2007-08-08%20flat%20tappet.pdf[/ame]

Amsoil source and other info:

http://www.thelubepage.com/