On the topic of "Royal Purple". . .
I was watching a hot-rod show on cable and they were talking about lubes that increase HP by reducing friction.
They dyno'd a z-28 and then did a complete oil/lube/fluid change with "Royal Purple."
Then they dyno'd again and got like 5-7 extra hp after the fluid change. I am sure Royal Purple is a sponsor but in theory it sounds sound and doable.
Maybe some somewhat cheap HP?
I haven't tried it.