If your goal is to keep your car in great shape, don’t even consider doing any of these things or you may end up causing serious and expensive repairs.
Never overfill the Tyres to “get better gas mileage”
The Internet has more than a few testimonials from people who claim they upped their mileage simply by inflating their tires to the maximum pressure listed on the sidewall. What they don’t tell you about is the rougher ride, premature tire wear, longer stopping distances and increased repair costs due to worn-out suspension components.
The recommended tyre pressure for your car is listed on a placard inside the driver’s door frame and it’s based on the weight of your vehicle along with the best possible handling. Inflating your tyres to the maximum pressure listed on the tire is okay if you’re hauling a very heavy load. But you must reduce the tyre pressure to the recommended pressure once you remove the load.
Never use the Wrong Coolant/antifreeze
Whether you do your own cooling system flushes or are just topping off your cooling system after a repair, using the right coolant is important to the life of your car’s engine and all cooling system components.
If you use the wrong coolant or mix two different types of coolant you can actually cause early water pump, radiator, heater pipes and heater core failure. This happens as a result of corrosion inhibitors which are designed to be compatible with the specific metals used in the engine and cooling system.
The damage may not show until you’ve racked up 5,000 or more miles. But when those parts fail, you probably won’t connect the dots and realize they failed because you used the wrong coolant.
Never mix up Brake fluid and power steering fluid
If you add the wrong fluid to either your power steering or brake system, the repair can be expensive. Power steering fluid swells the seals in a brake system, causing total brake failure.
Pouring brake fluid into your power steering reservoir is just as damaging because brake fluid isn’t a lubricant, so it causes pump and steering gear failure. Always double check before you refill your brake or power steering fluid reservoirs.
Never disconnect a battery cable to test the alternator
In the past, you could disconnect a battery cable while the engine was running to test the alternator in your car. If the engine continued to run, that proved the alternator was working.
But it’s a test you should never try on a modern car or truck equipped with computers and electronics. That’s because disconnecting a battery cable while the engine is running causes the alternator to spike a 25-125-volt surge within 40ms after cable removal.
That voltage spike can’t damage anything in an old non-computerized car, but it can instantly fry the many computers and expensive electronics used on all late model cars.
Repairing the damage can cost a small fortune. If your car or truck was built after the early 1970s, chances are it has at least one computer. So forget this old trick left over from the “old days” and test your car alternator with a volt meter.
Never drive when your oil light is lit
All cars have a “low oil pressure” warning light. If the light comes on while you’re driving, it can mean that your car is dangerously low or completely out of oil.
Furthermore, it can mean that your car has a serious leak that’s causing a pressure drop, a clogged oil passage that’s causing oil starvation, or the oil pump has failed or is failing.
Whatever the cause, when the light comes on, get off the road immediately and shut off the engine. Then pop the hood and check the oil level using the dipstick. If the dipstick shows you’re out of oil or dangerously low, you must add more oil before restarting.
Driving a car when it’s dangerously low or completely out of oil will destroy your engine in just a few minutes, and you may need an outright replacement.