You've probably always heard to warm up the engine before driving. But actually it's not necessary. Modern cars warm up quicker when driven. And the sooner they warm up the faster they deliver the optimum fuel economy, performance and emissions.
Premium grade gas is better for your car right? Actually most cars run fine on regular gas. Using premium in those cars does little more than cost you around an additional 20 cents per gallon. It won't hurt, but it won't improve performance either. A higher octane number just means that the fuel is more resistant to pre-ignition problems, which is why the hotter running, high compression engines found in many sports and luxury cars are designed to use it.
Change your oil every 3,000 miles is what the oil companies and oil change shops like to tell you. The truth is cars can go 7,500 miles before they need an oil change. Changing oil more often doesn't hurt the engine, but it can cost you a lot of extra money. Stick to the service intervals in your car owner's manual unless your car is being driven in severe conditions. Then, 3,000 miles is recommended.
Inflating tires to the pressure on the tire's sidewall is not recommended. That's the maximum pressure that the tire can actually hold. Instead, look at the automaker's recommended pressure which can be found on a sticker in the glove box or on the doorjamb or fuel-filler door. Check the pressure when the tires are cold, after the car has been parked for a while.
A dealership is not the only shop that can perform regular maintence to keep a car's factory warranty valid. As long as the maintenance items specified in the vehicle owner's manual are performed on schedule, any auto repair shop can do the work, and often for less money. Just keep the receipts to back you up in case of a warranty dispute on a future repair.
Dishwashing and laundry soaps should not be used to wash your car. If you like to wash your car yourself, always use a product formulated for that purpose. Household detergents can strip off a car's wax finish, which reduces the paint's protection.
Radiator coolant does not need to be replaced with every oil change. Most owner's manuals recommend changing the coolant every five years or 60,000 miles. Of course, if the level in the coolant reservoir is chronically low, check for a leak and get service as soon as possible.