Engine oil explained in detail and its choices. (Must Read)

[AudiDxb]

Oil Classifications.

There are basically two systems for oil classifications. The SAE viscosity grade (Society of Automotive Engineers). And the API (American Petroleum Institute) classification that designates the type of engines for which the oil was designed. The SAE viscosity grade is known as the “W” number when classifying oils. Most oils on the shelf today are multi-viscosity such as 10W30 or 20W50. In general, the lower the first number, the better the oil will perform in extremely cold conditions. Conversely, the higher the second number the better the oil will protect at higher temperatures. If you were driving in the winter in Dubai you would want the lowest number you could find like a 0W30. In our always hot climate however, a 10W40 or a 20W50 would be a better choice. The API designation is typically an “S” designation for gasoline engines and a “C” designation for diesel engines. Most of today’s oils carry an SH, CF or SJ, CF designation signifying that they are suitable for use in all gasoline or diesel automotive applications. Those of you with diesel engines should look for an API CG-4 rated oil. Which brand you buy is largely a matter of preference?

Synthetic vs. Petroleum based (Mineral) oils.

Synthetic oils were originally developed more than 50 years ago and became widely used in jet engines. Less than -80ºc ambient temperatures, 60000 shaft rpm, and 260º+C exhaust temperatures proved too much for conventional oils. Synthetics were created specifically to withstand these harsh conditions and to date every jet engine in the world uses synthetic lubricants. However, we don’t drive Jet engines in our cars here in Dubai, do we? Mobil 1, undoubtedly the most recognized name in synthetics, was introduced in 1976. Many companies have jumped on the bandwagon and have since released synthetic lubricants for automotive use and all are becoming increasingly popular for their superior lubricating properties, superior ability to flow at cold temperatures, and their ability to withstand high temperatures for extended periods of time. Several new cars including the Porsche 996 and the Chevrolet Corvette LT-1 are delivered with synthetic oil in the crankcase and require synthetic oil use throughout the life of the car.

There are two primary differences between synthetic oils and conventional petroleum oils. These are the base stock or liquid that makes up the volume of the oil, and the additive package. There are additives mixed in all oils that enhance the wear resistance properties of the oil, enhance the ability of the oil to neutralize acids and combustion by products, and provide corrosion protection for the engine’s internal surfaces. The amount and quality of these additives vary from one oil brand to another and this is a very significant factor in the ability of an oil to adequately protect your engine in all driving conditions. As a general rule of thumb, the cheaper the oil, the fewer additives it has and therefore, the less able it is to protect your engine.

There is one school of thought that suggests that the only difference in synthetic oils vs. petroleum oils is that the synthetics typically have a better additive package. This statement is only partially true. Synthetics almost always do have superior additives than petroleum oils. While this does add to the cost of the oil, it also enables the oil to last 3-5 times longer than conventional oil. The synthetic base stock however, is of paramount importance in the ability of a synthetic oil to flow at cold temperatures and withstand greater amounts of heat over significantly longer periods of time. Petroleum base stock molecules are long carbon chains that are sensitive to stress and heat. Additionally, various paraffins that are contained in all petroleum products regardless of how well refined they are, cause oil to jell like a syrup at extremely cold temperatures. At the other end of the temperature spectrum, high engine temperatures and heavy loads (as typically found in towing or racetrack applications) cause these chains to break down and the base stock actually boils off causing a change of viscosity and the formulation of sludge. This can happen at temperatures as low as 110º c and by 121º c many petroleum oils are suffering significant breakdown. Synthetic oils on the other hand are engineered specifically to provide all the lubricating properties that natural oil possesses, but none of the cold thickening or hot thinning properties of petroleum oil. Synthetics are made up of uniformly shaped molecules with shorter carbon chains which are much more resistant to heat and stress. Synthetics can withstand temperatures of 148ºc all day long and still protect your engine. In fact the American Society of Testing Materials (ASTM) standard wear resistance tests are conducted at 150º c. In this test synthetic lubricants far out perform petroleum lubricants by factor of four to one and greater.

Oil temperatures of 110ºc to 121ºc are not at all uncommon in summer time stop and go traffic with the A/C on. Further, temperatures on the cylinder walls and in turbos are often over 232°c for short periods of time. Cars can also have extremely high oil temperatures even though the water temperature may be normal. In some constant stressful driving condition (race track, offroad, towing) it is observed where the water temperature stayed right on 95ºc while the oil temperature fluctuated between 115º c and as high as 138º c depending on how hard the car was driven. The basic point of these numbers is quite simple that synthetic oils have a much wider operating temperature range, by design, than petroleum oils.

Economics of Synthetics vs. Petroleum Lubricants

Majorly all of the manufacturers of synthetic oil milk the benefits of reduced wear, more horsepower, lower operating temperatures, and improved fuel mileage. All of these benefits are derivatives of better cold flow characteristics and higher levels of friction reducing additives that are found in synthetic oils. It has been confirmed that better cold driving characteristics, increased fuel mileage of nearly 10%, noticeably lower operating temperatures, better heat dissipation capability, and long term high temperature stability with synthetic lubricants. Are these benefits enough, however, to persuade average drivers to give up their trusted petroleum oils and pay the extra price for synthetics? Enthusiasts, yes. Average drivers, perhaps not. However, synthetic lubricants can endure extended drain intervals, which is a major consideration toward justification of the higher costs. This benefit is not widely promoted by the major oil producers most likely because they want you to pay a premium for their synthetic oils every 5000 km just like their regular oils. Most companies don’t bother to tell you that synthetic oils are capable of going 15,000 km or more without significant breakdown. The short trips and stop and go city driving that most of do is much tougher on engine oil than over the road highway driving. In fact, frequent short trips (5 km or less) and stop and go city driving is considered by some raters as extreme and our cars need increased protection. Fortunately, we can achieve the superior protection and the economic benefits of synthetic oils while staying within the recommendations of our car manufacturers.

5000 km MYTH

The 5,000 km myth refers to a common belief that all cars should have their engine oil changed at least every 5,000 miles to maintain their car engine correctly. Whereas this is not necessary, and that people should follow the advice given in their car owner's manual rather than the advice of the oil-change businesses.

Which oil to pick for your Car?

Read your Car Owners Manual for finding specific grade of oil, manufacturer recommends.

As for the viscosity of oil to use, most new engines today require a multiviscosity 5W-30 oil for all-round driving. The lighter 5W-30 oils contain friction reducing additives that help improve fuel economy, and also allow the oil to quickly reach critical upper valvetrain components when a cold engine is first started. Most engine wear occurs immediately after a cold start, so it's important to have oil that is thin enough to circulate easily -- especially at cold temperatures.

For older engines and ones that are driven at sustained highways speeds during hot weather, 10W-30 or 10W-40 is a good choice. Heavier multiviscosity oils such as 20W-40 are for high rpm, high-load applications primarily and are not recommended for cold weather driving.

Straight weight 30W and 40W oils aren't very popular anymore, but some diehards insist on using them. They say the thicker oil holds up better under high temperature (which it does), increases oil pressure and reduces oil consumption in high mileage engines. But straight 30W and 40W oils are too thick for cold weather and may make an engine hard to start. They may also be too thick to provide adequate start-up lubrication to critical upper valvetrain components during cold weather. So switching to a straight 20W oil would be necessary for cold weather driving. Straight 10W oil can also improve cold starting, but is very thin and should only be used in sub-zero climates. A multiviscosity 10W-30 or 10W-40 will provide the same cold starting benefits of a 10W oil and the high temperature protection of a 30W or 40W oil.

For the ultimate in high temperature protection, durability and all-round performance, synthetic oils are the way to go. Unfortunately, most synthetic oils cost up to three times as much as ordinary petroleum-based oils. They cost more because synthetics are man-made rather than refined from petroleum. But this improves their performance in virtually every aspect.

Conclusion

Most major brand name petroleum oils perform adequately provided your driving conditions are normal and provided you change the oil regularly (remember, short city trips, driver’s ed track events, dusty conditions, and towing are considered extreme). Finally, for those of you who drive your vehicle hard, tow a trailer, drive very short distances, sit idling and in stop & go traffic for long periods, live in a hot climate and/or if your car runs hot, quality synthetic motor oil, synthetic gear lube, and synthetic automatic transmission fluid is a wise investment that will provide the additional protection you require as well as last thousands of km longer than conventional lubricants.

If you like this article, please share it with your friends as per statistics about 40% of engine problems, rebuild and failure happens due to poor engine oil maintenance.

[pokerface]

Good read and nicely explain the major concern and ever confusing area. Shared it on my fb so that i can educate with my dumb a$$hole colleague.

[magi111]

Excellent and informative article. Thanks for posting this. It’s informative and enlightening. Keep up the good work..

[warzi]

good must read i have seen soo many people confused over this topic