Something people forget to do is read their manual. Once upon a time oil change intervals were a recommendation of your local mechanic based on typical engine tolerances. Over time, engineers have built engines, sensors and computers that will tell you more about your car than someone poking around under your hood can.
Checking the manual, you’ll find very little about mileage. Mileage stress affects engines differently depending on how you drive, so it’s no use going by the odometer. For example, 20,000 km for someone who brings their car up to 70 km/h between the lights is going to stress the engine and thin out the oil faster than someone who cruises 20,000 km on the highway at 95 km/h all day long.
Most manuals will usually state “change the oil when the car’s computer/dash light indicates not exceeding 12 month’s between service” in other words, once a year or when the light comes on, whatever comes first. Manuals will also tell you at what oil health the vehicle can operate at safely. Modern combustion engines run safely at 15% oil health, high pressure engines can run at health as little as 10%. Again, check your manual for this.
You have to remember that, because of the system built around selling cars, dealerships sell at a very low profit margin (foreign imports especially). Most of the money is made through the service center. In the case of modern engines it’s selling oil changes at 70+ bucks twice a year (sometimes more) that cost them five bucks in parts and ten in manpower. I’ve seen friends walk out of dealerships with brand spanking new cars with a service calendar marked for every three months at about $160 per service. That’s an insane $640 every year. That’s not counting issues they may find during the visit (my ex was once conned into a $1,000 fluid flush for a car that was less than a year old).
I also suggest you always take the car back to the dealership when you get the oil changed. They will always use the recommended weight and volume by the manufacturer . They also have the proper OEM filters always in stock. I can’t count how many times I’ve seen people develop issues because a two bit mechanic used a “better” oil in their car. Now that you’re probably only taking your machine back once a year, saving that 10 bucks by using Jiffy Lube is negligible. Just remember to rip off that useless service sticker telling you to bring the car back in 6 months.
My answer may be two years too late, but you’re still better off if you check your manual and keep that advice for every car you buy from now on. It’ll save you money, time and the headache of waiting for your car every so often.