I have a 2002 Chevy Silverado 1500 pickup that just hit 250,000 miles. It has been great for the last 5 years I have owned it and is still running strong. I have never used any type of additive but with the mileage I was looking for advice on any type of fuel additive or anything anyone recommends that might be good for a truck with this many miles to use and what benefits it would add.

Run a can of seafoam in the gas tank every oil change. Have done it for years keeps injectors clean and will help with carbon etc.

Probably wouldn't hurt to take the throttle body off and clean it with a good throttle body cleaner using an old toothbrush. They can get some serious carbon build up over the years. Other than that and the seafoam mentioned above just keep doing what you have been doing because 250k is great!