General on going maintenance Lucas carb & fuel injector cleaner additives K&N Filter

[Smith007]

2002 ML 320 Km 220 000.00
I am one of the most distrusting individuals when it comes to companies marketing car additives.
BUT - in any event spoke to an individual who says he always adds on every 2nd. fill up: Lucas carb and fuel injector and claims it also lubricates the upper parts of the motor and even in his lawnmower (He has had 2 mowers in 20yrs - - mind you he may have postage stamp to mow or he might have conventional size lawn to mow - I don't know)
Any further recomendations?
or noticeable success stories or experinces in actually noticing
improvements?

PS I have been running a K&N Filter (air) and have experinced a feeling of up to 2hp increase and better fuel mileage