Did you have a problem with carbon buildup on the intake valves? I have owned my 4.6L for 21 years and it is fine w/o anything and what I can see in the engine it’s clean as can be in there. These cars have portal fuel injection which washes the intake of deposits or it should. I usually go up to 5,000 miles between oil changes and don’t need to add oil. I also use high quality synthetic oil 5W-20. Now other cars I own are direct injection which can get crusty build up on intake valves as this oil vapors condense out on the intake but with portal injection washing of the intake valve this seems pointless unless you sit hours in traffic idling maybe? What kind of oil are you using to boil off that much volume? How many miles? Keep in mind that that condensed oil would go through the engine as vapor if it didn’t condense into that can.
The first update I did on the can when just installed was about 5k miles and 3 months…it came out black, didn’t have time to sit around. This one doubled in time and distance driven. 🤷🏻♂️
