I put pressure gauges on both flatties, and the pressure readings didn't change when I made the switchover. Now, we don't always run 90+ temps in the Summer, but we get enough to make data runs
The 20-50 does as advertised. Has the viscosity of 50 weight when hot. Believe me, I was a skeptic, I've been running 50 or 60 weight since I was a pup.