slant 6 oil weight

But here are the top four that we have tested. Driven, Brad Penn, VR-1 and last but not least is Rotella T-4 & T-6 50-50 blend. I get asked all the time what do I use in my daily driver slant six and I use the 50-50 blend Rotella.
Why are you mixing Rotella T-4 & T-6 into a 50-50 blend? And are you mixing the same grade?