Now, every manufacturer offers its synthetic oil version and existing brands have been reformulated and improved.
There are more synthetic blends around, too. The blends are supposed to bridge the gap between true synthetics and regular oils, in terms of price and performance.
Synthetic oils do cost a bit more, but is it worth the extra money, you may be wondering? It is, and here is why…
Advantages of synthetic oil
A major advantage of synthetics is their ability to remain stable at high temperatures without breaking down or oxidising. Petroleum-based oils will boil away under high temperature. Other by-products of oxidation include tar, sludge and thickening.
While a petroleum-based oil will boil away as temperatures increase, a good synthetic, will lose only about 4% of its weight.
At higher temperatures, 475 degrees and above, conventional oils will volatise completely, while synthetics will still be lubricating at 700 degrees. Synthetics were originally developed for jet engine lubrication, and that’s why they have such high-heat breakdown resistance.
Eventually, all the oil in the crankcase will oxidise and breakdown, which is the reason for the typically recommended 3,000 mile oil change interval for regular oil.
The oil gets saturated with contaminants, but contaminants that are the by-product of the oil's own decay and not due to contaminants produced by combustion.
Synthetics don't need to be changed as often because they don’t decay like regular oils.
Practically every manufacturer uses synthetic oils now, and some even recommend a synthetic oil.
Discover how to change the oil on your specific vehicle
Film strength
Besides its resistance to viscosity loss at high temperatures, synthetics also have much stronger film strength. Film strength is the amount of pressure needed to force out a film of oil between two flat pieces of metal.
A good petroleum based oil measures at 500 lbs. while most synthetics are around the 3,000 lb. level.
This is important, because of its inherent higher film strength, there is much less blow-by past the rings and thus less oil contamination.
Lower temperature
Yet another benefit of synthetics is their ability to lower oil temperature in the crankcase. It is a well known fact that oil does not only lubricate but also serves as a coolant medium, drawing heat away from the engine's reciprocating parts.
However, as temperatures rise, petroleum based oils have a tendency to bead on the metal surface while synthetics will wet the entire surface, showing affinity for the hot metal rather than itself.
The lower oil temperature has the obvious effect of extending engine and oil life.
More horsepower
Besides all these attributes, synthetics offer less resistance so the engine produces more power, usually in the 2-3% range. Because there is less internal friction, an engine will use less gas, too, in the 3-4 percent range.
Mobil has been advertising that its newly formulated synthetics are even better than before. They’ve tested a new engine from the very start and at 300,000, the engine showed no measurable internal wear. At 1,000,000 miles there was wear, but the engine was still in good condition.
Most people are still leery when it comes to long change intervals, and if your car is still under warranty, you should not go beyond the manufacturer’s guidelines, unless the manual says you can if you use a synthetic. Oil changes typically recommended at 7,500 miles.
As for the blends, they cost about half the price of a synthetics. But what’s the point? And they don’t state what percentage their synthetic content is, either. If you’re going to use a synthetic, might as well use the good stuff.