Synthetic Oils: What are they and are they worth it?

Unlike conventional motor oils that are refined and distilled from crude oil, synthetics are manmade lubricants created from organic esters and other synthesized hydrocarbons. The special manufacturing process results in lubricants that outperform ordinary motor oils in virtually every aspect:

Superior temperature resistance. Synthetics can safely handle higher operating temperatures without oxidizing (burning) or breaking down. The upper limit for most mineral-based oils is about 250 to 300 degrees F. Synthetics can take up to 450 degrees F. or higher (some as much as 700 degrees F.!). This makes it well suited for vehicles that are operated in hot climates as well as heavy-duty, turbocharged or hard-use applications.
Better low temperature performance. Synthetics flow freely at subzero temperatures, pouring easily at -40 or -50 degrees F. where ordinary oils thicken and gel. This makes for easier cold starts and provides faster upper valve train lubrication during the first critical moments when most engine wear occurs. This is especially important with many of today's overhead camshaft engines.
Better Engine Protection. As motor oil travels through the engine, some of the additives can be sheared, literally cut in half, by high-speed engine parts, thinning the oil. Full synthetic motor oils resist shear under heavy loads better than conventional oils. This helps synthetic motor oil maintain its viscosity grade, enabling it to offer better engine protection and withstand more extreme engine conditions.
Lower oil consumption. Synthetic motor oils experience less "boil off" than conventional motor oils. A good synthetic will lose only about four percent of its weight when run at 400 degrees for six hours, compared to a 30% loss for a conventional petroleum based oil. The lower evaporation rate means less oil consumption between changes.
Cleaner engines. Synthetics don't break down or sludge up as fast as ordinary mineral based oils do. This means that the short trip to the store and back or a lot of city driving in the winter does not accumulate sludge in the engine as fast and lubrication efficiency is maintained.

Unfortunately, synthetic motor oil costs more than conventional motor oil because it is more expensive to manufacture. Some people question the economics of switching to the higher priced lube. The higher initial cost can be justified over the long run by better fuel economy, longer engine life and reduced maintenance costs.

Wayne's Garage does not recommend extending oil change intervals as much as a few of the synthetic oil manufactures do because of outside contaminates such as moisture, metal and particulates. However, if time constraints cause you to go over your normal service interval, synthetic oil will be in much better physical condition than mineral-based oil would be at that same mileage/time duration. We recommend replacing synthetic oil every 6,000 - 8,000 miles as opposed to 3,000 to 4,000 for regular oil.

Some Synthetic Oil Myths

Myth: I need to flush my engine before switching to synthetic oil.
No special preparation is necessary when switching from conventional motor oil to synthetic or from synthetic back to regular oil. You can even mix them.

Myth: Synthetic motor oils damage seals.
Untrue. Seals can actually last longer with synthetic oil.

Myth: Synthetics are too thin to stay in the engine.
Untrue. In order for a lubricant to be classified in any SAE grade (10W-30, 10W-40, etc) it has to meet certain guidelines with regard to viscosity ("thickness"). Synthetic oil will actually stay thicker in hot conditions.

Myth: Synthetics cause cars to use more oil.
Untrue. A leaking engine will leak the same amount of either. Unless an engine is a real oil burner, it will burn less synthetic than regular.

Myth: Synthetics void warranties.
Untrue. No major manufacturer of automobiles specifically bans the use of synthetic lubricants. Some are using it as factory fill in high performance engines.

Myth: Synthetics last forever.
Untrue. The additives still wear out and dilution degrades the oil.

Not all synthetic oils are equal Some give better protection and last longer than others, depending on whether they're formulated with Ester or PolyAlphaOlefin (PAO) stock. Synthetic oils made from the ester class are much more expensive, but are more durable and hold up under hotter temperatures.

Synthetic oils have different base stocks, which comprise some 90% of the oil. The base stock is the actual lubricant The other 10% or so is the additive package. The relative ability of oils to lubricate is determined by the components of the base stock. There are two principal classes of base stocks used in real synthetic oils: synthesized hydrocarbons (PAOs) and organic esters.

PAOs
The base stock materials used today many popular synthetic oils are made of carbon and hydrogen molecules. These
are synthesized from ethylene gas molecules into PolyAlphaOleflns (PAO). Almost all the synthetic oils sold in the stores are made with PAO base stocks. PAOs provide better viscosity characteristics, are more resistant to oxidation and have much better low operating properties than petroleum oils. PAOs are cheaper synthetic oil base stocks, and aren't as durable as the ester class of synthetic oils. Some of the popular brands of PAO oils include Amsoil and Mobil-1.
These are known as a Group IV oil.

ESTERS (Polyolesters)
Organic esters are made by reacting certain acids with alcohols, forming acid esters. There are alcohol diesters and
Polyol esters. This process uses expensive materials and results in lubricants that cost many times more than PAOs. Only esters are durable enough to withstand the rigors of jet engine operation and they are used in racing and high performance cars. These oils can cost $8 dollars or more a quart. Redline is an example of an ester synthetic oil. These are known as a Group V oil.

Hydrocracked (sometimes called Hydrowax)
These are petroleum oils that have been hydroisomerized, as it is commonly called. The most stringent level of petroleum oil refining. Much of the paraffin and impurities have been removed and its performance on any number of industry tests is substantially better than its group two cousins (the regular oil petroleum oil used in automobiles).
Although it is not made from a synthesized, engineered molecule and as such is not a true synthetic oil, it does offer a portion of the benefits you would expect from a true synthetic and in fact is usually sold and marketed as a 100% synthetic product. Hydrowaxes are very cheap to produce, even cheaper than olefins, making them the cheapest of all the synthetics. As they are formulated from crude oil base stocks they aren't a true synthetic. These are known as a Group III oil. Castrol Syntec is known for using this method.

Quality
Premium quality synthetics will blend more than one "species" of PAO and/or will blend these PAO basestocks with a certain amount of diester or polyolester in order to create a basestock which combines all of the relative benefits of these different basestocks.
This requires a great deal of experience and expertise. As a result, such basestock blending is rare within the synthetic lubricants industry and only done by very experienced companies. In addition, although such blending creates extremely high quality synthetic oils, they don't come cheap.

Differences in same Brands.

Even the same brand of synthetic oil can have different qualities. Mobil 1 has several different qualities available in the same weights. You can buy 5W/20, 5W/30, 10W/30, 15W/50 Mobil 1 in the "Extended Performance" line as well as in the "normal" line of synthetics for less than a $1 more a quart.

So what is the difference? Here's what the Mobil 1 website has to say about that:
"Mobil 1 Extended Performance formulas are designed specifically for today's longer service intervals and are guaranteed to protect for up to 15,000 miles or one year.
Mobil 1 Extended Performance has a unique formulation with a boosted level of protection and performance. Mobil 1 Extended Performance, with the Advanced SuperSyn* System, contains 50 percent more SuperSyn than Mobil 1"

This might indicate that the extended performance synthetic oil has about 50% more synthetic base stock than their regular "fully" synthetic oil. This would probably be a much better buy for the slightly increased cost.

*Mobil's definition of SuperSyn: "Mobil SuperSyn PAOs were developed to extend the range of conventional high viscosity PAOs and maintain excellent low temperature fluidity. Mobil SuperSyn PAOs are a class of high viscosity, high Viscosity Index (VI) polyalphaolefins manufactured by Mobil Chemical using patented, proprietary technology."