Most important maintenance?

Hello, I have a 03 Maxima with about 125,000 miles. I have had the transmission fluid changed around 60,000 and 1 of the spark plugs replaced when it started going bad. I was wondering what preventative maintenance would be most important to keep the car running as long as possible? Transmission fluid change/flush? Coolant change? Etc. Thanks!

As always, your best guide is the owner’s manual. If you don’t have it, order one. Either do a Google search or get one from a dealership.

The most important maintenance? Everything in the manual.

P.S. - Why change only one spark plug? They’re cheap; get the others too.

Never heard of anyone changing just ONE plug before. The diagnosis to find a bad plug is going to cost you more then replacing all the plugs at the same time. Plugs should be changed on a regular interval. And they should be replaced BEFORE they start going bad.

As SteveF pointed out…Check your owners manual. Maintenance schedule will be spelled out there.

And if you’re behind on your maintenance, get caught up. There’s a lot that should have been done at 125,000 miles.

“As long as possible” is going to be your problem. In a recent post a gentleman sunk $1600 in a 22 year old car only to find the addition repairs made the car not worth saving. Knowing when to stop is just as important as knowing what to do. As suggested following the recommended service intervals is the best starting place. Have your work done by a good mechanic familiar with Toyotas and ask when it is time to quit.

Always change spark plugs in “sets.” Changing one spark plug is something that a shady used car lot would do.

And at 125,000 miles I’m guessing they were all due.

I agree with the crowd. Take out your owner’s manual and do what the people who built your car wanted you to do.

As others have said, follow the owner’s manual. At 125,000, I would have the transmisison fluid and filter replaced, the coolant replaced, new spark plugs and air filter and an oil change and new oil filter. If you can identify the spark plug that was replaced, keep it for your lawn mower engine when you have the plugs changed.

It your '03 Maxima has a timing belt and it hasn’t been replaced yet, that is #1 priority. You can go to the gates.com web site to research your motor on whether it has a timing belt, interference engine or not, and timing belt change interval.

You haven’t said what maintenance has been done up to now. If that 60K transmission service is all you’ve done beyond oil, lube, and filter changes then you are overdue for lots of fluid changes (coolant, brakes, power steering, autp transmission, differential), and new plugs.

good news car has a timing chain

All spark plugs and wires
transmission fluid
oil
coolant
air filter(s)