When I purchased the RL WW the guy told me to use two bottles in a V8 engine. And I did see a big difference at running temp. Use to run between 'm' and 'l'. Now runs between 'r' and 'm'. Good enough evidence for me .
no real difference if you ask me....just make sure you make an 80/20 mix for the summer. should keep your car nice. lotsa people run a 50/50 mix and thats gonna overheat lotsa engines