if temparture were the case, a simple oil cooler is all that is needed to reduce temps so the oem could still run a 5w20. ever seen an oil cooler for an engine? its basically a large size transmission cooler. their nearly the same thing so its not like we are talking about adding much cost to a car. a single oil cooler and 2 lines dont represent much additional purchase price or assembly time compared to the rest of the car.