Motor oil is frequently referred to as the lifeblood of a vehicle, and this is definitely one saying that is quite true. Driving around with dirty or old oil can affect just about every aspect of performance. Perhaps it's because oil is such a critical part of auto maintenance that it has attracted quite a few myths and rumors over the years, many of which have simply no basis in fact.
Part of the reason for the myths surrounding motor oil is simply the evolution of the industry. Things that your father or grandfather believe about oil may well have been true in their day, but oil has advanced quite a bit since then. The introduction of synthetic motor oil, for example, was met by resistance for many years, primarily by people who believed that it was "fake" or somehow inferior to regular oil.
That couldn't be further from the truth. The term "synthetic" does refer to artificial processing, but the oil is still derived from crude, just like regular motor oil. Still, for many years synthetic motor oil was blamed for engine burn-off and leaks, along with just about every other thing that could go wrong in an engine.
In reality, using synthetic oil is no different from using regular oil. Really, the only thing that drivers have to worry about is the viscosity and performance requirement as recommended in their owner's manuals. As long as the synthetic oil matches these guidelines, the driver should be set to go.
There's also a prevalent myth about the usage of this oil. Some say that using any type of oil that was not originally in the car will void a manufacturer's warranty. Others claim that drivers should not switch between regular and synthetic - once one type is in the car, that's the type that the car needs for life. These are both false - in fact, you could even mix different types of oil as long as they are of the same viscosity.
Another area where drivers run into trouble is when they start to ignore their owner's manual. Some drivers may have heard the "thicker is better" theory or think that they need to use a different type of oil based on the temperature where they live.
Manufacturers list a certain viscosity and grade of oil for a reason. Deviating from this recommendation is asking for trouble - and may very well void your warranty if it's discovered. It's true that thicker oils can be beneficial for older vehicles that have aging parts, but it's not really all that helpful as many drivers believe. There are also numerous benefits to thinner oil, such as improved fuel economy, and better engine starting in colder temperatures.
In general, however, automakers put a lot of thought into the type of oil they recommend for a vehicle. Some may recommend different types depending on the temperature range or the type of driving being done. However, this is really unique to each vehicle. Some drivers become very set in their ways and say things like "I've used straight 30 weight all my life." What may have worked on engines and cars in the past is likely asking for trouble on modern vehicles. This is why it pays to read the owner's manual thoroughly when you purchase a new car. The performance gained from deviating from the manufacturer's recommendation is not worth it when considering the additional problems it may cause.