When it involves the proper care and feeding or our cars, there seems to be two kinds of people: proactive and reactive. Reactive people wait for definite signs that repairs are needed, like grinding noises or non-running engines, and react to it. The reluctance to spend is understandable, but since some repairs are inevitable, simply prolonging them is often counterproductive. Proactive people have preventive maintenance done on schedule, including inspections and monitoring of wear and tear. The result is often smaller repair bills when the inevitable time comes to make a repair.
For instance, if someone waits until the brakes make grinding noises before getting them fixed, they will probably need new rotors along with new pads, possibly costing twice as much as doing them before the grinding started. Here's the point. Both of these people are going to have a brake job done eventually, but the one who waited too long is going to have a more expensive repair job. The trick is to know how long a particular part or group of parts will last, and that can be tricky indeed. Your owner's manual and your mechanic can help, your uncle Harry's past experience with his car might not.
For instance, when forecasting the remaining life of brakes, mileage doesn't mean much. Some people get 70,000 miles or more on a set of brakes, some get only 20,000 or less. It's not miles that wear out your brakes, it's how many times you stop. Interstate driving is easy on brakes, city driving is tough. A mechanic can check the amount of lining remaining, and based on the number of miles you have driven, he will hazard a guess how many you have left, assuming the same type of driving. Note the words "hazard" and "guess." Stretching it too near the guess can be hazardous to your health, and wallet.
Many engines now have rubber timing belts. Most manufacturers recommend replacing those belts at 90,000 miles. Your owner's manual will tell you if yours is different. Past that point, the belts will slip or break. Some engines will simply stop running, and the belt will have to be replaced. Some engines, however, will suffer catastrophic damage if it breaks. It's a poor choice to be reactive about. Also, on many engines, the water pump is driven by that same timing belt. Since the pump has the same miles on it as the belt, it is nearly worn out, and since the labor operation to change the pump is the same as for the belt, it would be a smart move to change the water pump with the new belt, for very little extra expense now. Conversely, if the pump should fail before the belt does, it would be a good time to change the belt. Being proactive here will save you lots of money. Your car may not have a rubber timing belt. Some engines have steel timing chains. These engines almost never need new chains, so if that's the type you have, you're free to worry about a few other things, like ...
All engines still have other belts that need attention. They are rubber and drive the accessories like power steering and alternator and air conditioning compressor. They deteriorate from miles driven and from age. Most are now the serpentine style, which is a flat belt with grooves. They are very strong, but they do need to be replaced every three years or so, especially before a long trip. If they break, you will be stranded, and sitting along the interstate is no fun. They sometimes make chirping noises. Never put any coating on them. Belt "dressing" chemicals will cause even louder chirping noises. They might be too loose. Most, but not all belts, have automatic spring loaded tensioners. If the belt is too loose, the tensioner must be replaced. Some are still mechanically adjustable for belt tension, but it should be professionally done. Too tight, and bearings will be damaged in the auxiliary equipment. Too loose and the belt will slip and burn up.
Be proactive with preventive maintenance and your bills will be smaller. Do nothing and the repair expense might bite you in your reactive butt.