I have a 2000 Marquis LS 4.6 liter 85,xxx miles as of Jan 20011. I purchased from origional owner(all previous service done at the Mercury Dealer) runs sounds great. It was tuned up and checked over last Summer by my regrular mechanic. Prior to the tune up I noticed my gas milage had gone down a little from 24 highway to about 22. I get a little over 300 miles to a tank of gas city. I had inquired at the Mercury dealer just prior to purchaseing the car 3 years ago at 68,xxx miles to find out if it was due for any service, I was given all previous repair recipts from origional owner. The Merc dealer said since the car only had in town miles rarely any highway miles it might need fuel system service. When my mechanic checked the car out just after purchase he found no problems he suggested fuel injector cleaner every 4th tank of gas. He recomended Lucas but he uses megapower injector cleaner that was only available thru one of his distributers. He said he didn't think it needed fuel system service, said it wouldn't hurt but he thought it was the dealership selling service. He was not knocking the dealer. The only problem I have currently is my drivers side Catalytic converter has started to rattle(I'm told its the converter not the heater) and no estimate of how long until it fails. Aparently when it fails I will know because it will loose some acceleration. Any suggestions on best injector cleaner, brand of gas(I use Shell), maybe a fuel system cleaner.

 

When fuel injection first came out in the late 1980's there was some problems with dirty fuel injectors needing cleaning. But the problem quickly disappeared with better injectors & gasoline formulated to keep fuel injectors clean.

As long as you are using major brands like shell, you don't need any additives. My 91 ford 150 has never had any fuel problems, & it has 120,000 miles on it.

Using additives won't hurt anything, but I have never seen any results from using them other than it lighten my pocket book. About the only people I know who recommends fuel additives are those who either make it, or sell it.

As long as it runs well, just drive it. You can also be like my sister. If it starts making noise, just turn the radio up until you can't hear the noise anymore.