You should be checking your coolant level, your brake fluid level, your power steering level, you are transmission fluid level, and your engine oil level. You should know where they are. You should have checked all of them at least once, properly. If the vehicle is over 100,000 miles or let's just say five or six years old you should have already completely changed the coolant, the transmission fluid whether it is manual or automatic, any differential fluid, steering fluid, brake fluid, and the coolant.

Once you're at 10 years and over 100,000 miles you should be looking at suspension, bushings, and links, struts, shocks, and definitely new rotors and brake pads.