My car is a 2005 PT Cruiser with 63k miles. Prior to my ownership, its OCI was around 4k miles with 5w-30 conventional (no specific brand). Recently, after pulling the stick at 3k miles on the most recent change, the oil was pretty dark so I decided to clean out the engine. First, I ran Valvoline Two-Part Fuel System Cleaner (the link is for the old three-part; the new system negates the throttle cleaner and incorporates it into the delivery system) for the 20 minutes it took to run its course. This included the fuel injector treatment in the tank. After that, I added one pint of Heartland Oil System Cleaner to the old oil and ran the engine for ten minutes, whereupon I drained the crankcase. When the oil was mostly drained, I added a quart of 5w-30 to push the old oil out of the sump, completely drained all oil, replaced the filter, and added five quarts of conventional 5w-30 and ran it for another ten minutes to clean out the engine flush. After draining that and replacing the filter once more, I finished it off with five quarts of MaxLife full syn and another oil filter. So, what do you think? Effective, at all?