I was in the Plumbing /Heating and AC business for twenty five years and I always tried to get people to save money. First of all why pay someone to come to your house and clean your A/C unit when it is running fine. It is easy to clean and maintain yourself. Don't let them talk you into a maintenance program. The money you pay into that could be used if and when your unit needs replaced. If you already change your filters every 60 days and especially if you have upgraded to a pleated filter the indoor unit needs very little maintenance. It has been years since I saw an oil port on the fan motor it is self-contained and needs little maintenance. Twice a season turn your outdoor unit off and use a spray bottle filled with a liquid soap and spray the outside good. Rinse it out with your hose. If this is not something you want to do then hire someone, but stay with them and make sure they do the job. Don't let them talk you into replacing your unit. I have serviced many that were over twenty five years old. The savings isn't there. So what if it is twenty or even thirty percent cheaper to run. The pay out isn't there till it needs replacing. It could take you twenty five years to see the savings. Are you going to be there twenty five years? Can they promise you in the next couple years they won't be back with a new and better unit. You won't see the benefit if you sell your home. You won't save that much in electricity. The air conditioning unit built thirty five years ago is still being built today, only in a newer looking package. Unless you have a lot of disposable income save it.