Originally Posted by spiderbypass
" I think Valvoline Modern Engine is a carbon deposit cleaner, Valvoline Advanced Synthetic is a carbon deposit preventer."
Wouldn't this be the opposite? Would think the Modern Engine formula would be for newest vehicles so would be more focused on preventive measures. Conversely would think the Advanced formula would focus on cleaning older engine deposits-
Maybe though your point was there is less carbon deposits with non-Gdi engines so prevention is better choice since active cleaning is not needed.
Valvoline Advanced Synthetic is a much newer formulation than Modern Engine. Checking the specs on Valvoline's PI sheets it appears that Advanced Synthetic, no matter what viscosity, has low values for NOACK, VII, KV100, sulfated ash, etc all things that contribute to lower carbon buildup according to many experts.
Valvoline Modern Engine has lower SAPS and, according to Valvoline claims, a detergent that can break up carbon deposits after they form.