Maintenance is fact of life for owning automobiles. The manufacturer includes a preventive maintenance schedule for each vehicle and this schedule is found in the vehicle owner's manual. While it doesn't hurt to perform maintenance more frequently than what the PM schedule recommends, it's more important that the vehicle receives regular maintenance. For newer OBDII vehicles, this maintenance mainly consists of oil and filter changes, older vehicles also included more frequent tuneups (points & condenser replacement, new or cleaned sparkplugs, etc). The maintenance schedule might seem a bit complicated and filled with jargon, but it's really quite simple and the maintenance items form a pattern. If you don't have a manual, it can often be found on the internet.
While it might seem the simplest to take vehicles back to the dealer for service because, after all, who knows your vehicle than them, this is not the case. The one who knows you vehicle best should be you. As a example, I brought my 2002 Camaro to the local dealer (Falls Chevrolet) for its 37,500 km service. I told the service adviser that I brought my car in for its scheduled maintenance, which included an oil change and the flush & refill of the cooling system. When I got back home, I noticed that the tires were not rotated. When called back to complain, the service manager told me that they normally rotate the tires every 10,000 km and I should have told them that it needed a tire rotation. Although I was just bringing this oversight to their attention, they basically told me to take my business elsewhere. So much for customer service!
Local independent garages generally have a lower shop rate than a dealership and include more services. They often include free inspections, top up fluids, and rotate tires as part of an oil change. They aren't doing this to be charitable. They're really out on a fishing expedition and they're looking for problems that can bring them some additional follow-up work. The wheels have to come off to check the brakes and it doesn't take any more work to rotate the tires when the brakes are inspected. When the shop recommends repairs, make sure you get them to show you the problem and don't be shy about getting a second opinion. Everyone wins this way. You just need to make sure that bring your car in for service when it is required.
The oil change intervals commonly recommended by most shops is 5000 km (3107 miles). According to the BobistheOilGuy (BITOG) web site, this can be too frequent. Good quality oil should only be changed when the used oil analysis indicates that the oil is worn out. This is more work and expense than most vehicle owners want, so we recommend following the vehicle manufacturer's advice for oil & filter change intervals and viscosity. GM vehicles are now equipped with a built-in oil life monitor that takes driving conditions into account and GM recommends that oil be changed as indicated by this monitor. According to some members of the BITOG forum, this oil life monitor does accurately indicate oil life.
For newer cars, synthetic oil is often a worthwhile additional expense. For older engines, a good non-synthetic (with sufficient ZDDP additives) might be a better alternative (see Oil for Flat Tappet Engines for more information. Synthetic oil is recommended whenever possible because starts off as a single higher viscosity oil and its molecular structure gives it low lower viscosity when cold without the use of viscosity improving additives. Dino (or conventional) oil also starts off as a single low viscosity oil but additives are added to give it higher hot viscosity. Dino oils (actually Group I & II) oils depend upon polymer additives to turn a single viscosity oil (like 10W) into a multi-viscosity oil (like 10W-30). A 10W-30 synthetic oil is a 30 weight oil that is created to structurally behave like a 10W oil when cold without polymers. Therefore a synthetic oil will have relatively constant viscosity over its entire life while a dino oil will become thinner as its polymers break down from shear and then become thicker with oxidation and soot build-up.
The Corvair article goes on to mention that older engines should not use oils with an API Starburst. This is reduced phosphorous oil is designed for use with newer engines equipped with catalytic converters. The author recommends that in most cases, the oil and filter may be safely changed every 6 months or 5000 miles (8047 km) or even longer with synthetics. For the antique or classic car owner, the oil should be changed more frequently if the engine is generally driven on short trips that do not allow the engine to reach operating temperature.
Filter changes are also an important part of maintenance. Although high flow air filters (like those made by K&N) are touted for their positive effect on performance, nothing is free. The lower pressure drop (for higher flow) means that these filters let more dirt through. Stick with high quality filters (like Wix and Baldwin) for maximum oil life. Oil filters usually changed with the oil even though the manual often recommends every other oil change. Air filters are easy to change and your autoparts supplier can fix you up with a filter you can change in a matter of minutes at a significant savings.