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GIVEN all the motor oil options out there, choosing the right oil for your car might seem like an impossibly daunting task. While there is a mountain of info to learn about the various oil choices, the first step is hon- estly quite simple: Look in the manual. Your car's owner's manual will list the recommended oil weight, whether that's a stand- ard like 10W-30 or something more unusual. Choose an oil with the recommended weight from a brand that displays the starburst symbol that indicates the oil has been tested by the American Petroleum Institute (API). In addition, there's a two-character service designa- tion on the container. API's lat- est service standard is "SL." SL refers to a group of laboratory and engine tests, including the latest series for control of high- temperature deposits. Next, you need to choose the viscosity (thickness) that's suit- able for the temperatures your vehicle normally operates in (again, check your owners man- ual). Those are the basics. But there's a whole lot more to the story than that. Understand the labels These are the labels you'll find on every container of reputable motor oil. The API donut on the right tells you if the oil meets the current SL service rating (C for diesel engines). It also provides the SAE (Society of Automotive Engineers) viscosity number and tells you if the oil has passed the Energy Conserving test. The starburst symbol on the left in- dicates that the oil has passed the tests listed for SL service. Viscosity Viscosity means a fluid's re- sistance to flow. In motor oil, it's rated at zero degrees Fahrenheit (represented by the number preceding the "W" [for winter]) and at 212 degrees (represented by the second number in the viscosity designation). Motor oil thins as it heats and thickens as it cools. So, with the right ad- ditives to help it resist thinning too much, an oil can be rated for one viscosity when cold, anoth- er when hot. The more resist- ant it is to thinning, the higher the second number (10W-40 versus 10W-30, for example), and that's good. Within reason, thicker oil generally seals bet- ter and maintains a better film of lubrication between moving parts. At the low-temperature end, oil has to be resistant to thick- ening so that it flows more eas- ily to all the moving parts in your engine. Also, if the oil is too thick, the engine requires more energy to turn the crank- shaft, which is partly submerged in a bath of oil. Excessive thick- ness can make it harder to start the engine, which reduces fuel economy. A 5W oil is typically what's recommended for win- ter use. However, synthetic oils can be formulated to flow even more easily when cold, so they are able to pass tests that meet the 0W rating. Once the engine is running, the oil heats up. The second number in the viscosity rating – the "40" in 10W-40, for example – tells you that the oil will stay thicker at high temperatures than one with a lower second number – the "30" in 10W- 30, for example. What's really important is that you use the oil viscosity your car's owner's manual recommends. Why so many oils? Look on the shelves in auto parts stores and you'll see oils labeled for all kinds of specific purposes: high-tech engines, new cars, higher-mileage vehi- cles, heavy-duty/off-road SUVs. In addition, you'll see a wide se- lection of viscosities. If you read your owner's manual, you'll know what the car manufac- turer recommends for a brand- new vehicle. The manual may include a reference to Energy Conserving oils, which simply means that the oil has passed a lab test against a reference oil. It's no guarantee of better fuel economy, but most of the lead- ing brands have at least some viscosities that are so labeled. Let's take a look at the different types. How to choose between synthetic and conventional motor oil Premium Conventional Oil: This is the standard new-car oil. All leading brands have one for service level SL, available in sev- eral viscosities. The car-makers usually specify a 5W-20 or 5W- 30 oil, particularly for lower temperatures, with a 10W-30 oil as optional, particularly for higher ambient temperatures. These three ratings cover just about every light-duty vehicle on the road. Even more impor- tant, though, is changing the oil and filter regularly. A 4000 miles/four months interval is good practice. The absolute minimum is twice a year. If your car has an electronic oil-change indicator on the instrument cluster, don't exceed its warn- ing. Full Synthetic Oil: The oils made for high-tech engines, whether in a Chevy Corvette or Mercedes-Benz, are full of syn- thetics. If these oils pass strin- gent special tests (indicated by their labeling), it means they have superior, longer-lasting performance in all the criti- cal areas, from viscosity index to protection against deposits. They flow better at low tem- peratures and maintain peak lubricity at high temperatures. So why shouldn't everyone use them? Answer: These oils are expensive and not every engine needs them. In fact, there may be some features that your car's engine needs that the synthetics don't have. Again, follow your owner's manual. Synthetic Blend Oil: These have a dose of synthetic oil mixed with organic oil, and overall are formulated to pro- vide protection for somewhat heavier loads and high tem- peratures. This generally means they're less volatile, so they evaporate far less, which re- duces oil loss (and increases fuel economy). They're popular with drivers of pickups/SUVs who want the high-load protection. And they're a lot less expensive than full synthetics, maybe just pennies more than a premium conventional oil. Higher-Mileage Oil: Today's vehicles last longer, and if you like the idea of paying off the car and running the mileage well in- to six figures, you have another oil choice, those formulated for higher-mileage vehicles. Almost two-thirds of the vehicles on the road have more than 75,000 miles on the odometer. So the oil refiners have identified this as an area of customer interest, and have new oils they're rec- ommending for these vehicles. When your car or light truck/ SUV is somewhat older and has considerably more mileage, you may notice a few oil stains on the garage floor. It's about this time that you need to add a quart more often than when the vehicle was new. Crankshaft seals may have hardened and lost their flexibility, so they leak (particularly at low tempera- tures) and may crack. The high- er-mileage oils are formulated with seal conditioners that flow into the pores of the seals to re- store their shape and increase their flexibility. In most cases, rubber seals are designed to swell just enough to stop leaks. But the oil refiners pick their "reswelling" ingredients care- fully. Valvoline showed us the performance data of one good seal conditioner that swelled most seal materials, but actually reduced the swelling of one type that tended to swell excessively from the ingredients found in some other engine oils. You also may have noticed some loss of performance and engine smoothness as a result of engine wear on your higher- mileage vehicle. These higher- mileage oils also have somewhat higher viscosities. (Even if the numbers on the container don't indicate it, there's a fairly wide range for each viscosity rating and the higher-mileage oils sit at the top of each range.) They also may have more viscosity- index improvers in them. The result? They seal piston-to-cylin- der clearances better and won't squeeze out as readily from the larger engine bearing clearanc- es. They also may have a higher dose of antiwear additives to try to slow the wear process. If you have an older vehicle, all of these features may mean more to you than what you might get from a full synthetic, and at a fraction of the price. M4 maltatoday | SUNDAY • 17 FEBRUARY 2019 MOTORING Picking the right oil for your vehicle Check your car manual for which type of oil best suits your vehicle