I have a 2006 Ford Five Hundred Sel with 83,000 miles on it. I have concerns that the mechanic that it was taken too did not do the job that he should have. Like I said its 2006 in great condition for its age. I notice in the manual that the car is due for a big check-up at 90,000 miles. But considering its age should I have already changed the spark plugs as well as have fluids changed and refilled. Thank you all for your help.

 

Considering the manufacturers recommendations are based on general use, it never hurts to have them performed a little sooner.
If you reside in an area where you get some pretty high or low temperatures, always a good move to have the work done at your convenience even if a little sooner.

 

Are you asking if you should have to 90K service done now or what?
I will not recommend mileage based flushes/tuneups until 5K before the recommended mileage, that way the customer has time to plan for the work in the near future, customers will throw a major fit and go down the road of I am going to call cooperate/let me talk to the GM/ect if we recommend stuff early.
You say your concerned the mechanic did not do whatever job he was suppose to, what job did you request/pay to be done? If a customer comes in and asks for a 90,000 check up we would break the checkup down into individual parts and get approval for each part instead of giving them a single large bill that covers things maybe done elsewhere recently.

 

Think you ought to get the fluids changed early because you're trying to take care of a low mileage car, especially brake and power steering fluids, radiator coolant if they haven't been done. When I have tranny fluid serviced, I now always go to the dealer because of a past experience with an independent shop putting in the wrong fluid (despite assurances at the start). Tranny is expensive.

Spark plugs only wear through mileage, not through age. If you look down the list of year 2020 threads here you'll see one that has photos showing original 2006 Ford 500 spark plugs at 231,000 miles and were still working with no misfires - although the electrodes were very worn. So the stock plugs last.

Welcome to the forum, Charles Lane.

 

Something I have noticed, The engine may run with little or no misfires, but,,,,,,,increased plug gap requires higher voltage to jump the gap and this can put additional stress on the ign system and performance does suffer.
I can assure you they didn't just pull the mileage recommendations out if the air . They did some durability testing to come up with the recommendations.
Some folks can even notice the difference when new plugs are installed.