Premium gas for winter time ? PZEV knock
One can easily understand how extremely high engine temperatures, summer heat, heavy loads, and high rpms ... might recommend the use of premium gas.
I found out that the Part of the PZEV system actually creates engine knock on extremely cold starts! The system is manipulating valve timing, injector timing and injected duration.
“ brief and subtle knock of the valves during cold starts, especially in low temperatures.”
I’m going to suggest that to protect yourself from these pollution controls one might consider premium fuel use in the winter.
Just a thought and maybe it makes sense and maybe it doesn’t.