May also depend on how tight your motor is to what viscosity oil would be best.
Personally I don't like most 10W-30's in a high performance motor during extreme summer temps and long trips. I'd use 10w-40 in the summer and 10w-30 in the winter or possibly 5W-30 if you drove your car alot below 32 degrees. 5W-30 is easier on cold startups in winter.
1970 FE5 Duster 360/904/3.91's SOLD
1973 TB3 SpaceDuster 340/4spd/4.10's SOLD
Moparless for now but when the opportunity is right I'll have another one.
I'd use 10w-40 in the summer and 10w-30 in the winter or possibly 5W-30 if you drove your car alot below 32 degrees. 5W-30 is easier on cold startups in winter.
