You can actually dyno with higher results with lower weight oils. Try running Ow-30 oil.
YOu will dyno a few hp more, but I'd personally take the power loss for more protection. Also, keep in mind your drivetrain oils. For example, on SE-R's, the trannies are notoriously weak. When you get big power, they like to blow up and one of the ways we've been able to postpone this is by using Redline Heavyweight Shockproof oil, which is like 150W. It takes like 45 minutes to put in 4 quarts of the stuff. It's like Pepto Bismol. This stuff robs easily 5-6 hp.
Terrin
92 SE-R
13.2@104