I can get it at Costco, but in the States, I always see it in the automotive section of Walmart.

 

Some autoparts stores carry it and I have even bought it by the bottle at Chevron stations.

 

I also drive a Trans Am and we use GM Top engine cleaner(dealer only) or SeaFoam.(NAPA).

I know gas is better now than it used to be but when I treat my car alot of carbon comes out. A huge smoke screen and we only run Super / Premium . I run regular in my RX because when I put super it didn't run that good.

Just to let you know it is recommened before a tune-up because you will need new plugs and a oil change after a treatment

Stephen