When at the local auto parts store or auto service station, some may have noticed the bevy of synthetic oils available though at higher cost than normal oil. There are many synthetic oil benefits, but there are some drawbacks for some people.
Longer life among synthetic oil benefits
Synthetic oils, according to Car Craft magazine, are extensively engineered to better withstand extreme temperature and pressure that occurs within engines compared to normal mineral oils. On a molecular level, synthetic oil has a more stable, uniform structure compared to traditional mineral oils, which are more prone to vaporizing and combustion at higher temperatures.
The benefit is that synthetic oil doesn’t lose viscosity, the resistance to motion under stress or “shear.” In other words, synthetic oil doesn’t thin as quickly as mineral oils. Thus, oil changes needn’t be as frequent. Distance between oil changes can be anywhere from 5,000 miles, according to AOL, or in some cases, according to HowStuffWorks, up to 20,000 miles.
Longer-lasting viscosity leads to smoother, better operation, according to Car Craft, which can result in less internal wear and longer engine life.
The importance of tolerance
Synthetics are not as well suited to higher mileage engines and older cars, as synthetic oils are “thinner” liquids than mineral oils. Early synthetics git a bit of a bad rap for precisely that reason, according to Popular Mechanics; when synthetics first appeared in the early 1970s, some car owners found them problematic. Engine seals would shrink due to the thinner oil and leaks would occur. Modern synthetics don’t have this problem.
Modern engines, according to AOL, are manufactured with much tighter tolerances, the spaces between parts. Synthetic oils are ideal, as more lubrication is available in less space. Some cars makers mandate owners use synthetics or blends, called semi-synthetics, for precisely this reason. For instance, the current Chevrolet Corvette is only supposed to use synthetic oil. Engines with higher mileage don’t have as tight of tolerances, nor do older engine designs, so synthetics are better for later model cars.
Fewer changes, longer life
Synthetic oils contain fewer contaminants, according to Car Craft, which leads to less sludge in the engine. They also flow better at lower temperatures, meaning start-up, the most stressful part of engine operation, is easier on the engine even in sub-zero temperatures.
The potential life of the engine is also extended. Smoother operation leads to less internal wearing of parts and some extremely-high mileage car owners will swear by them. Peter Gilbert, a man who became famous for putting more than one million miles on a 1989 Saab 900 SPG, religiously used synthetic oil, according to Yahoo.
Mobil, according to the Guardian, bought a brand new BMW 325i in 1990 to prove the potential of its synthetics. The car was placed on a dynometer and ran at 85 miles per hour every day for four years and ran the equivalent of one million miles, with technicians performing every recommended service according to BMW’s schedule. When the engine was disassembled after the one million mile mark, it was still virtually at factory specifications.
Popular Mechanics: http://www.popularmechanics.com/cars/how-to/products/4213451
The Guardian: http://www.guardian.co.uk/technology/2009/oct/25/bmw-325-million-mile-motor