I would appreciate your opinions on whether or not it is worth it to get the local Honda (or anybody else) dealership to professionally clean my fuel injectors. I live in canada and have 228,000 kms on my Honda civic. I use good gas and routinely use fuel injector cleaner but I notice that the mileage is very gradually starting to drop. Is this due to the car simply getting older and running less efficiently or is it due to dirty injectors or fuel filter slowly becoming plugged.