Great question, and I don’t take it that way at all. Mostly it’s because it has all the red white and blue colors on it and checkered flags and stuff, the Mobil even says NASCAR on it.
No, it’s because I’m extremely distrustful of the “rebuild “ after driving it. It runs low oil pressure sub 30 in warm weather with 10/40 in it. I didn’t rebuild it, I bought it this way. But I don’t know how much attention to detail it had on the bottom end and suspect more bearing clearance than should be. So, I’m going with thicker/more expensive oil. Not expecting anyone to agree, but it’s what I’m doing.