Don't these 2 oils now have the same formulation and performance? If not, what's the difference?
They are made by the same company, but they like to claim that the products are different. My guess is that they have very minor differences in order to maintain plausible deniability concerning whether they are identical.
I thought I heard someone say one has an infineon add pack, and another has a lubrizol add pack.
Could be wrong.
I'd say Pennzoil is the better of the two but both would give you long engine life.
I either buy QS or Mobil Clean 5000 at Walmart. Both cheap/good oils.