Did you see the thread on some of the zink taken out of
oil? Kroyer engines had problems with mobil one and I went with valvoline , 468 shelby in my car , and have no problems. Temp runs up to 195 in car. I also run 407 all alumi twin turbo ls1 in my dune buggy , and its a heavy car that is lugged and turned to 6500 rpm in desert temp, temp in car up to 225 at times with no problems. My zo6 corvette as you know is 427 small block all alumi and temp up to 225 and has a 100,000 mile warranty, maybe sub contractor for Roush had problems, I say this because Roush knows how to build first class power and want customers happy, but i get parts that have be sent back or wrong all the time. Chevy has problem with bad rocker arms on zo6 engine, needle bearings fall out, just a bad batch on a few engines. Roush will find and fix.