Just for the record, you don't get 10W-30 by mixing 10 weight
oil with 30 weight
oil, you get something closer to 20 weight
oil. Both multi-viscosity and straight weight oils get thinner as they get hotter. The multi viscosity oils (thanks to additives) just thin down less.
I'm always amazed at how many Cobra owners prefer heavier oils even though most of us have oversized crankcases and oil coolers. I know if someone came out with a 20W-70 oil There would be a rush to pour it in. I always wonder how much of the oil some guys are pumping is just going out the bypass.
Just my $0.02
Bob