Originally Posted by Concillian
It was Redline, and, as mentioned, brand new oil acted the same. The new oil was not Redline. Knowing it was potentially a really short interval I used the cheap stuff, normal 5w30 GTX I use in my wife's oil guzzling Corolla, but I'm pretty sure that didn't shear to the same point in 25 miles of freeway driving. Brand new 5w30 should be higher than 8-10 psi @ hot idle.
With the new oil, I think I have pretty much ruled out oil dilution and shearing.
if the two oils mixed and the gtx didnt like the residual rediline in the engine...then yes, that could cause it
My suggestion would be to change the oil and filter again and see if that fixes the issue...that would eliminate that as possible