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Synthetic Oils - Are They For You?

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On: Tue, Aug 30, 2011 at 10:19AM | By: Peter C Sessler

Synthetic Oils - Are They For You?

You’ve probably heard a lot about synthetic oils, good and bad. Still, there are things you should consider, before you decide which is better for your car – conventional or synthetic oil. First, now every manufacturer offers their 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.

There are lots of reasons why you should consider synthetics.

A major advantage of synthetics is their ability to remain stable at high temperatures without breaking down or oxidizing. 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 volatize completely, while synthetics will still be lubricating at 600 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 oxidize and breakdown, which is the reason for the typically recommended 3000 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.

Several manufacturers use synthetic oils. Porsche uses Mobil 1 and has 15,000 mile oil change intervals. This includes their turbocharged model. Corvettes use synthetic oil exclusively, too. I’ve been using synthetics for years now, with 12,000 mile oil change intervals.

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 lb. while most synthetics are around the 3000 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.

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.

Besides all these attributes, synthetics offer less resistance so the engine produces more power, usually in the 2-3 percent 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 their newly formulated synthetics are even better than before. They’ve tested a new engine from the very start and at 300,000 miles, 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. All I can do is pass on my experience, our AWD Grand Caravan now has 227,000 miles, and I’ve been changing the oil every 10-12,000 miles (filter every 5,000) and the engine runs like a top.

As for the blends, they cost about half the price of a synthetic. My feeling is, 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.


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