1. ENGINE COOLANT AND ANTIFREEZE
How Often: Check twice yearly, once before summer and again before winter; change if coolant has brown tint or rust bits.
Pay Now: Free to check; up to $5 to top off with correct mix of water and coolant or antifreeze. If you don’t use the right coolant for your car, you could damage your engine.
Or Pay Later: Without coolant, you can damage the water pump ($50 to $100) and possibly your engine.

2. OIL
How Often: Check monthly; change every 3,000 to 6,000 miles
Pay Now: Free to check; $20 to change yourself (oil, disposal fees); $20 to $40 at a shop.
Or Pay Later: Not changing the oil can void your warranty. Increased wear will shorten the engine’s life span. Rebuilt engines cost $1,000 to $3,000, plus labor, depending on the car.

3. AIR FILTER

4. TRANSMISSION FLUID AND FILTER

5. BRAKE FLUID

6. TIRE TREAD

7. TIRES FOR PROPER INFLATION

This list has been severely abridged. To read the full list, view the original post at it’s source:
7 Things To Regularly Check On Your Car To Save Money (Consumerist)