Hello 50,000 mile service,
From owning many cars over 45+yrs, I would not worry about the stock Hyundai Spark Plugs. There are more important items to service.
1). Change your front brake pads and bleed your complete braking system from rear to the front. Every car I’ve own needed new front brake pads around 50K-60K. Don’t wait until with wear the rotor and push the caliper pistons out.
2). Service your radiator. Just perform a drain and refill with stock antifreeze. This will take 4 qts or 2 gallon. Do not flush or use radiator flush on 50K car. Antifreeze, radiator, engine should still be clean. Just keep it all clean with a drain and refill. Do not forget to replace the radiator cap, these fail at lower pressures, usually around 4-5 yrs.
3). Perform an oil/filter change, use the latest synthetic oil API SN Plus or API SP.
4). Perform a Transmission drain and refill, remember to clean the magnetic plug.
5). If there is a front diff., drain and refill with syn gear oil with friction modifiers.
6). Rotate your tires and have them balanced. Get your 4 wheel alignment.
7). At 50 K and 4-5 yrs old, change your battery. Bad Battery can damage alternators/regulators.
8). Inspect your Acc. Belt.
9). Put on some new widow wipers. Fill your window washer fluids.
10). Clean and grease all your hinges, hood, doors, trunk, and lub your key slots and latches.
11) Change your air filter and cabin filter.
12). Perform an injector service, DIY use Chevron Techron in 2-3 tank fills. Then use one every oil change.
After you’ve completed those services, then perform a mini-tune and clean your spark plugs.
