[fastball]

Again there’s no sin in changing your fluids and spark plugs as early and often as you want other than wasting your own money. But don’t ever let a dealer or mechanic tell you it’s required or your warranty is void or your car will blow up.

Truth is as well engineered as modern cars are today resulting in longer service life and fewer required maintenance components, dealer service departments aren’t as busy as they used to be so they make a lot of stuff up hoping for gullible customers.

The original 1967 Camaro SS 350 required a carb adjustment, cap and rotor adjustment, and full set of spark plugs every 15-20,000 miles. Spark plug technology was the dark ages then. All that mechanical stuff goes out of calibration after some time using it and the car will start to run like crap.

Modern technology has virtually eliminated all of that. Oil changes can go 5,000 miles or more, spark plugs are good for 100k, coolant good for 150k, and obviously fuel injection, computerized engine management, and electronic ignition coils have eliminated the carb and distributor.

The service department today is really like the lonely Maytag man waiting for something to just break.

OP - if I were you I’d film your mechanic changing the rear diff fluid and bring that video to your dealer, along with the invoice that he probably won’t charge you more than $50.00 to do it...... and show them both to the dealer. Your dealer can choke on it “$1300 because changing the rear diff fluid is so hard or time consuming” my ass.

That’s the kind of crap that gets fists into noses.