Originally Posted by lsmkr01
I run Chevron Techron fuel system cleaner before every oil change and do minimal city driving. The cleaner removes buildup and all those contaminates go into the oil so its necessary to change the oil after that tank full. Also, stretching the engine out (use the entire rev band) often and running Shell 93 V-power religiously has had all my BMWs running like champs.
The engine piston rings prevent the loosened contaminates from mixing with the engine oil. Their purpose is to seal the combustion chamber from the crankcase. When you remove fuel injector contaminates using fuel system cleaners they are sometimes pushed out with the exhaust and some might become additional
contaminates on the spark plugs. Because you are using fuel system cleaner added to the gasoline it works to help clean fuel injectors not the spark plugs. The mix ratio of cleaner to fuel reduces the cleaning action compared to EFI cleaning machines and direct application combustion chamber cleaners.
When using fuel injection cleaning machines
and strong combustion chamber cleaners it is sometimes
worth changing the spark plugs after completing the cleaning process.