Throughout the steady development of the automobile over the past century, oil has often been regarded as one of the prime components. Why? This is because it facilitates the otherwise intense action, between metals. The engine, being constructed mainly with metal, works well with oil. It prevents heat and friction from being generated from the rubbing metals. Oil allows these to push, pull, press or slide smoothly. More specifically, engine components such as pistons and camshafts efficiently function up and down the cylinders without hindrance.

Thus, being undoubtedly one of the major factors, it should be monitored; in this case, changed regularly. This would ensure that the engine will remain in top condition and perform optimally - less wear, more fuel efficient and quicker acceleration - to name a few benefits.

So, amidst all these reminders and precautions, why then should oil be changed in the first place?

Oil inevitably accumulates dirt and other sticky deposits. While clean oil ensures that the engine performs at a high level; dirty oil contributes to its decline. Ignoring such measures over an extended period of time will result to gradual, but noticeable loss of performance, poor fuel economy and increased emissions. There are various types and scopes of recommended manufacturer's maintenance check-ups, ranging anywhere between 5,000 to 10,000 kilometer intervals. From their end, this also ensures that their products will perform well, which is good for the company. Practicing good preventive maintenance habits, such as regular oil changes, is a relatively easy way to protect against premature engine wear. However, what is a common understanding is that regardless of the type of oil, all of these inevitably deteriorate, wear out and get dirty. It has become thick and abrasive over time.

So, the clearest and simplest answer to the earlier query is: oil should be regularly changed to maintain efficient lubrication.

Apart from the oil per se, changing the oil filter is also a requirement in periodic preventive maintenance. Its essential function is to ensure that only clean oil is supplied into the engine. The filter efficiently captures almost all solid contaminants. However, as time passes and kilometers increase, the dirt accumulated by the filter block the smooth oil flow. The oil then breaks down and does not lubricate as well anymore. This is the reason it has to be regularly replaced too simultaneously when the oil is changed.

So what will happen if the oil is not changed regularly?

The dirty oil will cause long-term damage to the vehicle, such as overheating, high fuel consumption and black smoke emission from the tailpipe. The vehicle will not accelerate as quick and will rev too high, even on relatively low speeds. The deposits inside the engine will thicken and harden, causing more restrictions and blockages in movement and circulation, causing other parts to inevitably fail as well.

It is not enough to merely change the oil and filter every 5,000 kilometers or so. Moreover, understanding what kind of oil to use for the correct type of vehicle and other subsequent conditions are just as important. Perhaps just as important as choosing the brand to buy; is being informed about the different oil specifications, such as its viscosity rating.

The oil's viscosity rating is determined by the internationally-recognized Society of Automotive Engineers (SAE). Oil viscosity refers to how easily oil pours at a determined temperature. It is then measured and referred to by a number, which is also known as the weight or thinness/thickness. Thinner oils are like water and thus pour smoother at low temperatures than heavier, thicker oils. The lower the viscosity rating or weight, the thinner the oil; while the higher the viscosity rating, the thicker the oil. Thin oil's advantage is for cold starting and friction reduction. On the other hand, thick oil's advantage is for maintaining film strength and oil pressure at higher temperatures and heavier loads.

The ratings of these typical and commercially-available oils usually range from 0 to 50. The W after the number refers to Winter grade oil, representing the oil's viscosity at zero degrees F. The low viscosity oils that pour faster at low temperatures usually carry rates of 5W, 10W, 15W or 20W. On the other hand, the higher viscosity oils which are thicker usually have SAE 30, 40 or 50 grade rating.

For instance, a low viscosity oil designed for colder weather will not provide as much lubricating efficiency as an oil designed for warmer weather. Conversely, a high viscosity oil such as SAE 30 or 40 would relatively be stiff at lower temperatures, preventing the engine from starting immediately.

However, here's the good news. Current advances in technology have propelled automotive and oil manufacturers to minimize the gap between the two general types of oil viscosity. These are generally-referred to as multi-viscosity oils, which are generally for normal driving conditions. These try to capture the best characteristics of each, without overly-compromising the other. Although for more extreme conditions, the more specialized oils are still the ones to be used. To a certain extent, it also flows well at low temperature for easier starting yet retain enough thickness and film strength at high temperature to provide adequate film strength and lubrication. This explains the reason oils having a wide viscosity range.

Now, as kilometers inevitably continuously increase, the efficiency of the oil and the engine decrease. This is the inverse proportion in engine efficiency: the higher the usage, the lower the efficiency. As the vehicle accumulates wear and tear over time, over 100,000 kilometers in the odometer for example, some manufacturers recommend motorists to switch to oil with slightly higher viscosity in order to reduce noise prolong engine life. The thicker oil will maintain the oil film strength and efficiency in the bearings. More oil pressure in the engine will lower engine noise and minimize generated fatigue in the bearings.

Perhaps to underscore the value and importance oil plays in the automotive industry, the American Petroleum Institute or API, monitors the different aspects of oil - like performance level, viscosity and energy conservation. It tests, sets and maintains standards through the various segments of the industry. These undergo strict specifications and are subjected under severe situations, in an effort to simulate the daily grind the vehicles go through everyday. The API works closely with the different manufacturers and even recommends inputs and results which are objectively based. The API's consensus standard is one of its successful programs.

Meanwhile in Europe, the European Automobile Manufacturers Association or ACEA, represents many major vehicle manufacturers in Europe. Though competitors in the market, they collaborate together in order to achieve the standards by which efficient practices are thoroughly observed across the industry. Its members are the big players in the automobile industry, cooperating in order to further push and ensure the development, maintenance and upkeep of the different sectors, including EU legislators. It was formed in order to address the various individual and collective issues of the industry, including, technological advances and technical support.