You mean less viscous. Viscosity is essentially a resistance to flow. Just an fyi :beer:I Run 10w30 Mobile 1 in my car. 5w20 IMO would be to viscus and would overheat quickly in a turbo application. I think some guys are running even heavier oil than i am.
Run what the motor likes...
Cost to replace a turbo: $2,000
Cost to replace a motor: Way more than $2,000
I always run 5/20 motorcraft oil never had a problem,and i beat the shit out off my car all the time stock motor close to 45000 miles.
I'm running regular ole conventional Valvoline 5-30. I was told to do so because the blow-by issues when running a synthetic oil.