The carbon build up seen on most N54 BMW engines is due to the nature of Direct Injection. Direct Injection engines seems to suffer heavy carbon buildup. BMW even has a special tool that used in conjunction with an air blaster/walnet shells and a shop vac cleans out the carbon (after removing the manifold).

Heavy carbon buildup can cause knocking and ticket (enough buildup and the tolerance between the top of the piston and the valves goes out the window).

All this talk of gas types is really irrelevant. Deposit buildup forms quickest when the engine has an issue. Many of us have head intake manifold gasket problems (a known issue), some of us have had fuel injection problems, and many others that cause the engine to run lean, or rich. It is under those circumstances that Deposits form. Same goes for driving hard before the engine has come up to temp.

Additionally, driving before the cats come to operating temp also causes issues, blocked or fouled up cats..

If it's ticking, pull one of the plugs (or all of them), and go rent a scope and look to see what the cylinders look like, and then go from there.

I didn't see Sunoco listed as a Top Tier gas. Kind of surprised. I was under the impression it was one of the best out there.

Max - is the car still pinging? Are you sure it's an internal ping?

Wouldn't Sunoco just fall under the petro brand now? All the GTA sunocos have been branded petro canada for a while now.

I don't know. I was hoping someone could provide clarification because it's my go to gas station for my cars. I like to consistently use the same place. Little superstitious I guess.

It is in Canada (or at least Ontario). It was actually Suncor Energy (Sunoco) that bought Petro Canada, but they decided to rebrand all of their stations to Petro Canada instead of Sunoco. Same gas, just a differnt name.

Another thing I recently noticed is that now all Esso stations in the GTA have 93 octane fuel. Happened in the last few months. No complaints so far.