Originally Posted By: kr_bitog
Originally Posted By: chevrofreak
Get it clean, then lube it up.
The UCL in theory should help prevent the injectors from gumming up again.
Agree, but the determination process whether already clean or not is not easy without scope inside the combustion chamber.
Premium fuel normally comes with good dose of UCL components.
As a long time UCL user, Chevrofreak is correct. Clean it, then lube it. If the car has more than lets say 20,000 miles on it I would run a good FI cleaner first. Once you're finished with it add your UCL, that should keep things in good working order. If the car is used in short runs then a FI cleaner could be used before it has 20K on the clock. This is what has worked for me.
The interesting thing with any additive, oil or gas, is the average person has no idea the condition of his engine internals unless he opens it up and looks. So knowing exactly when to use a FI cleaner is a guess, but prior to moving to a UCL I would dose the car with a good FI cleaner to play it safe. I'm not sure if Premium Gas contains a UCL, it should provide better cleaning than regular gas. Opinions vary on that along with the brand of gas.
YMMV