I will share what a service advisor at a dealership told me. I asked him about service schedules and how important it was to stick to the directions in the manual. He leaned in and said, look, I am about to quit so I will let you in on a secret. Dont do anything! and I mean anything! Unless your car or truck tells you its time. Vehicles today are much smarter than we are. They are set up to tell you when fluids need replacing, rotations to be done. Dont waste your money, do what your vehicle tells you to.
I was like, WOW! Why does it take someone quitting to get an honest response. Anyway, that is what he told me, that is what I do. Also, save yourself a ton of money and wasted time at the dealership, change your Hemi oil at home in the driveway. Supplies cost about $35 and takes all of 45 minutes.
Hope that helps.
I change oil every day on customers' cars and trucks. You really believe the computer for when to change the oil? OK, get this: I know that the computer uses many aspects of an algorithm to determine oil change time, and have seen variances of 3400 miles up to 10000 miles on the same car at different times. The times Ive changed the oil on this car, and several others like it, where the mileage was nearer the 10000 mile mark, the oil drained out frothy and thick and jet black.... nasty!
Cars are not "smart". The marketing and actuarial personnel of the manufacturers are the smart ones. They need their jobs. They make claims that are absolutely false.... like "lifetime coolant"... uh, yeah, sure! They know the average age of a car, they know the lazy side of human nature.... And the manufacturers bet on folks neglecting and/or destroying their cars so the new car market will thrive.
There is no such thing as transmission fluid, coolant, or any other maintenance item that is "lifetime".
So, where's the middle ground (I've digressed slightly)? There have been improvements to many of the products we use in our vehicles, but none are impervious to exposure to temperature extremes, mechanical stress, or humidity/water exposure. How much water condenses inside your engine, transmission, brakes, differential, in high humidity after you've driven your car and gotten everything really hot and dry, then park the car and let it cool off? Not much at a time, but it is cumulative and damaging.
The variable, likely, is time. How long is one committed to keeping a car or truck? What is their motive regarding the extended warranty/maintenance interval? I mean, does one wish to do only the very minimum to stave off a claim denial for the warranty? Or is one thinking in the long term... such as keeping the vehicle for 20+ years? This would be the consideration for whether or not to do maintenance more or less frequently, if at all. I wouldn't want my car to have to have a repair if I could have avoided it with timely maintenance.
As a benchmark, I'd service the automatic transmission every 60K miles. I'd change the oil at no more that 5K miles. I'd flush the coolant, replace the thermostat, and put on a new radiator cap every 60-70K miles. Serpentine belt? Replace it at no more than 60K miles. Brake fluid should be replace every 2-4 years depending on humidity levels. Differential oil should be changed at 60K intervals too. These intervals aren't engraved in stone. Non are. Not doing these things is like jumping over a dollar to pick up a dime. These intervals have kept many of my customers in their cars for over 15 years and over 300 thousand miles.
As a final point, extended warranties used to have a pro rate on them. I've gotten a lot of cash back the few times I had the warranty and either sold the car or the car was totaled.This was not a well known fact, but it was in the fine print. (I actually read it!) It never mattered if claims had been levied against them. And, it pissed the dealer off that I knew it. In one instance, my daughter had totaled her car (A '94 Cavalier) She was in college (1999) and several expensive claims had been honored for repairs. We went back to that same stealership to buy her an newer used car, and I knew that I had $1800.00 Pro rate credit due me. The finance guy's blood absolutely boiled when we went in for final negotiations and I pointed out that I knew it, and insisted it be deducted from the sales price! That was slush that he intended to keep. You must read all your fine print. Read your policy thoroughly and without interruption. That's where you will find your answers. Also, call the extended warranty company with any questions before you need to make a claim. They'll be happy to help.