Quote from DC dealer after purchase, "If you leasing use regular but if you own it and plan to keep it use premium".

The thing is that you don't hear detonation until the knock sensor has reached it maximum range of possible correction. The engine is detonation on regular, computer back up the timing, adds more fuel, it operating within the range and you don't hear a thing. Over the long term the crown of the pistons will develop small pin holes from the detonation. You are also more likely to develop deposit/carbon build up in the combustion chamber on regular (less additives). Those two things will create even more hotspots and it will slowly gets worse over time then you will start to hear detonation. The end will not be too far behind. I have taken many engines apart and have seen what detonation will do to pistons.

IMO like the dealer said if you plan to keep it, do your engine a favor, and use premium. Its the long term effect of using regular that's going to hurt.

Like the famous quote about changing your oil "Pay me know or pay me later"...