Mr. Kilmer, I have two turbo GDI cars, one is a 2015 Mustang eco and a 2018 accord. what is the gasoline additive you recommend to reduce the buildup from GDI?
what is the gasoline additive
There is none. That's the whole point. Gasoline is already a good cleaner. Because the gasoline is injected directly into each cylinder, the gas (or any additives you put in) does not have the opportunity to clean the valves and intake. GDI engines need to be walnut blasted on a regular basis to keep them clean, which significantly adds to maintenance cost. That's why it's a bad idea to buy cars with GDI engines.
How about any intake products?
No. Mechanical removal with high pressure is the only method that works.
Mechanic in a can won't save you this time.
If it were my vehicles, I would put a high quality catch can on them to mitigate the carbon build up on the back of the intake valves. Some automakers like Toyota address the carbon buildup issue on their GDI engine by employing both port and direct injection. They spray gasoline on the back of the intake valve in that setup to “wash” the buildup away: It’s more complex but that’s their solution (it’s been around since the mid 2000s on some of their Lexus products).
If you use a catch can, realize it can potentially void the powertrain warranty claim (or at least make you fight harder). Also, if you are in a state that does smog check/inspection, you would have to remove the catch can beforehand and then put back on later. In addition, you have to periodically check the catch can and empty it out - just more maintenance hassle.
