Almost all the new cars use 5w30 as there oil, the tighter tolerance with advanced machining has made that possible.
They use it because of less friction, greater fuel economy and more horsepower. Fred Johnson Reno, NV Phil Wrote: i tried 15/40 and it actually gave me more revs at take off so much so i thought about more pitch onn the prop however when hot i did not like the oil pressure i like to see 10psi / 1000 rpm so went back to 20/50 interesting though more power on thinner oil phill
