1. The first resolution is one that you really should be doing already. Change your oil every 5,000 miles (or the recommended interval in your owner’s manual.) This is something that is vital to the longevity of your engine, but can sometimes get overlooked. If you do your own oil changes, make sure to write down the mileage somewhere you’ll be sure to look before it’s time to change the oil again. There is a reason they put the sticker in the corner of the windshield, where you are bound to look.
2. Brake fluid. I am going to say go ahead and replace it because most likely you are past the recommended interval. The recommendation to replace brake fluid is once every 2 years or 20,000 miles. Yes, that seems excessive, but brake fluid is hydroscopic, meaning it absorbs moisture in the air. This is to help keep the brake lines from corroding from the inside; but over time it also lowers the boiling point of the fluid, which can lead to brake fade. Any time a major brake component is replaced (caliper, wheel cylinder, HCU) the shop who does the repair will normally go ahead and flush the system. Check your service history, and if you haven’t had it flushed in the past few years, it would be a good idea to get it done.
3. Check the condition of the coolant, and possibly flush it also. Coolant is another fluid that can get overlooked by a lot of people. The coolant not only controls the operating temperature of the engine, but it also prevents corrosion from building inside the engine/coolers, and prevents freezing (hence “antifreeze”). Coolant has additives blended in it that do wear out over time, and the coolant breaks down. This can cause radiators, oil coolers, and EGR coolers (for our friends with 6.0’s) to get plugged up, and need replacement. The recommended interval for coolant will vary with manufacturer, but is generally around 100k miles. Even if the coolant still “looks” good, it is best practice to flush it anyways. Ethylene glycol, a popular agent in antifreeze; is poisonous to humans and other animals, so be sure to dispose of used coolant properly.