Shell Tests Lubricants to Extremes
Choosing the proper motor oil is no longer as easy as buying a jug of milk. It used to be that you could simply settle on a suitable weight for the ambient temperature and pour it into the crankcase. Engine lubricated. Problem solved. Not anymore. Buying milk might remain simple but consumers, especially performance enthusiasts, are now faced with more choice than ever when it comes to motor oil.
While it’s true that there are more engine oils on the market than ever before, the basic functions (lubrication, wear prevention and cooling) remain the same. So what’s the big deal? It’s because lubrication technology has to keep up with engine technology if it is to retain an adequate level of protection. Just because those old smallblocks ran happily all day long on conventional straight 40 weight oil doesn’t mean the same stuff will keep your modern high-revving low-tolerance engine alive for long. Add to that the extreme heat created by turbocharging and it’s easy to see why conventional oil won’t cut it.
Motor oils are a blend. That means that the base stock oil, which is either mineral (from dinosaur fossils) or synthetic (man-made), is mixed with a variety of additives in differing proportions to improve the oil’s performance in certain areas. It’s the addition and subtraction of the different additives that makes a particular motor oil package more or less suitable to specific conditions. In the past the right blend was attained by trial and error. These days, like everything else, the recipe is created with computers. The result is motor oil finely tuned to provide the best balance between engine protection, engine performance and fuel economy. So what are some of these additives and what do they do?
For starters, VI (viscosity index) improvers allow the lubricant to be thin enough for easier cold starts but stay thick enough at operating temperature to maintain an adequate cushion between moving parts. In 5W-30 rated oil, the 5 refers to the oil’s viscosity at 40° C and the 30 refers to the oil’s viscosity at 200° C. Detergents are added to keep the oil clean and reduce sludge and engine deposits. Dispersants are used to suspend foreign particles in the oil, which prevents coagulation (or clotting), which can lead to blocked oil passages. Bad news. Rust inhibitors and pour point depressants (which lower the temperature at which oil will still pour out of the bottle) are also standard ingredients in virtually every modern oil blend.
The additives just listed are common to most motor oils but it’s the following few that really separate performance oil from the regular stuff. Antioxidant additives keep oil stable during high temperatures so it can continue working properly even after intense driving sessions. Friction modifiers help make the oil slipperier; less friction equals more power. Finally, anti-foaming agents are used to suppress air bubbles, which can especially occur at high RPM. Oils suitable for high performance street engines will have additive packages that lean more toward engine protection (better anti-foaming capability and more antioxidants) while no-holds-barred racing oils will sacrifice engine longevity for all-out power by increasing the amount of friction modifiers to make the oil as slippery as possible. Make sure the oil you choose contains an additive package most suitable to your hardware and driving habits.
Emerging engine technologies continuously introduce new materials that require motor oil manufacturers to stay on top of their game. In order for oil to do its job it has to be designed to work with whatever material it’s being used with. Traditionally this has been iron and aluminum. But the engine in the new Nissan GT-R, for example, employs a plasma coating on the cylinder walls. Such technology was once reserved for the likes of Formula One but stands to gain popularity in the consumer market and, as it does, will need lubricants with additive packages that can accommodate. Oil producers will have to update the oil’s various properties so that it can continue to do its job properly over the new surfaces. With the current resurgence of factory turbocharging and the unprecedented number of ultra high performance factory and aftermarket tuned engines, choosing high quality oil with the right additives is more important than ever.