YES, mixing anything with fuel wont help you. Why? Because of how fuel flows into cylinders.
In direct fuel injected cars (like Panamera), fuel does not flow over the valves, which would help clean them, and keep them clean.
In direct fuel injected cars fuel is injected into the cylinders below the valves, never touches the top of the valves.

In non DFI cars, fuel is injected into cylinder, from fuel injector, onto top of the valve, past it, into cylinder. Since fuel flows over the valve, the chemicals you put into gas help clean valve tops.

 

fuel additives will help with build up in the cylinder, but wont do anything for the buildup on the back of the valves as the others have noted.

 

Just did a slightly modified intake valve cleaning using the CRC Intake Valve Cleaner.

I did not have a second person to rev the engine to 2000 RPM. First time I tried spraying I held the button too long and the engine immediately stalled. Not comfortable driving the car I took another one to go on an errand, (took my dog to the veterinary oncologist). So essentially I let it soak like with what little I sprayed in for a few hours. When I got back I started it up again and it was idling somewhat poorly. I drove around for 20 mins.

I tried again with short bursts. This seemed to work so I kept at it until the can was empty. I did most of the can with the can upside down as the instructions note not to have it sideways for some reason, which is how I had it maybe 1/3 of the can. After I felt the can was empty I went and turned off the engine. I reconnected the Y pipe to the intake manifold and tightened it down. I waited 1 hour and drove it around town in sport plus mode. This keeps the engine RPMs higher than even driving around on the freeways in comfort mode. I did this for 20 minutes. When I started off there was engine roughness, and after about a block and a half I heard some slight metal clanking, which then went away about a 1/4 block later.

Note, when I yanked the Y pipe no check engine light! I'm going to have to update the other thread, my new suspect is the Pennzoil Platinum Euro, which lost it's A40 approval rating 11/19...

 

Anyone know how to turn over the engine so each cylinder gets to TDC for manual cleaning please? Do I have to go underneath? Thanks!

 

Get a socket that fits the center of the balancer on the crankshaft. Rotate the engine.

 

So I realized spraying the intake valve cleaner into those ports that two cylinders are open at a time. The 6 remaining cleaner pooled around the closed valve. I suctioned out most of the fluid pooled in those 6, but I have cleaner in the two cylinders. I guess continue to put car back together...

Anyone else who loses the clip my parts guy at DTLA was really sharp and found the connectors. I transfered the clip over:. 443-906-232

 

Finally got to performing this yesterday...got the whole bottle in the car...it ran rough for a bit then I let it soak for a couple of hours. Upon starting the car...smoke poured out the rear, clearly this was doing its job...took the car on a nice 15 minute drive and got the speeds well above 70mph...maybe a little higher . But all in all, I definitely feel better throttle responsiveness. I'm impressed, the bottle did say do this every 10K miles which may not be a bad idea.

Thanks to all who shared their experiences. I do have the Check Engine light...and will likely clear with the Durametric.

 

Can the old carbon residue somehow mix with the engine oil with this procedure? aka is it best to do this just before an oil change? Or this can be done at any time with no issues?

 

I was worried about clogging the catalytic converter or fouling the downstream O2 sensor(s). Car fired up just fine. I should go back in and do the two valves that were open to the cylinders but haven't...