Wayne, I am using 0W-20 in my HCH.
My partner has an 02 Civic EX for which the manual calls out 5W-20.
I was wondering if 0W-20 would improve his mileage and be safe to use.

Maybe 0W-20 was just not available back then.

Need fewer troops to support.
Drive a hybrid.
Best tank 71.65 MPG.

Before this car I spent two years learning hypermiling on my 2004 HCH1.