I've been getting a lot of mail regarding using synthetic motor oil in vehicles. Questions such as:

- Should I use synthetic oil?

- Does it work better in some cars than others?

- Does it cost more?

- Do I have to change the oil more frequently?

Less frequently?

- Does it make my engine last longer?

First of all, let's take a brief look at the history of synthetic motor oil and its introduction to the marketplace.

Amsoil Inc. developed the first synthetic motor oil to meet American Petroleum Institue (API) service requirements. Retired Lt. Col. Albert J. Amatuzio, President and CEO of Amsoil Inc. witnessed synthetic lubricants in action as a jet fighter squadron commander. Synthetic oils were developed for (and still are used exclusively in) aircraft jet engines because of their extraordinary capacity to reduce friction and wear on engine parts.

Synthetic oil has an incredible ability to function dependably at severe hot and cold temperatures as well as withstanding rigorous and lengthy engine operation without chemical breakdown. This is critical in aircraft engine operation because, if oil breaks down at 30,000 feet, aircraft engines can fail and well, you get the picture. Amatuzio decided he would develop synthetic motor oil to be used in automobiles for the same benefits.

In 1972, Amsoil introduced the first synthetic motor oil for automotive applications. In the early 70s, another company was also working on synthetic oil development for the automobile: Mobil Oil Co. They came to market with synthetic motor oil in 1975. By the 1990's, the other major oil companies added their synthetic oils to the marketplace, in addition to their petroleum-based products.

To understand synthetic motor oil, let's look first at the origins of all motor oil.

Conventional oils come from crude oil that is pumped from the ground. In an oil refinery, crude oil is separated into various fractions. These fractions become the bases for lubricating oils and fuels. The part of crude oil that forms thick, tangled masses of carbon chains are used in roofing tar and roadwork. Very short chains and ring compounds of carbon are volatile and can be refined to produce gasoline and other products.

All motor oils are made up of base oils and additives. In general, fully synthetic motor oils contain non-conventional, high-performance fluids. Synthetic blends usually use some non-conventional, high-performance fluids in combination with conventional oil. It is the unique chemical formulation of synthetic oil that causes it to be highly resistant to viscosity breakdown from high temperature, friction, and chemical contaminants.

Should I use synthetic oil in my car?

That depends on the vehicle's age, mileage and the carmaker's recommendations. Older vehicles with high mileage tend to have excessive mechanical wear in the engine, allowing for internal oil leakage. For vehicles with high mileage, it is not recommended to use full synthetic oil because it is thin and very free flowing, and use of it does (more often than not) result in internal oil combustion.

I used full synthetic oil in a Plymouth Neon. After logging 120,000 miles the car started to consume oil at an alarming rate. Concerned, I switched to a semi-synthetic oil that was more full-bodied and the consumption stopped. I logged another 30,000 miles and sold it. It's still running with more than 200,000 miles today and it doesn't burn oil.

Carmakers use full synthetics and semi-synthetics in some of their engines today. In most cases, you will find that a synthetic lubricant is used when there's a high-performance engine with tight engine tolerances, high compression and high operating temperatures. Follow your owner's manual for motor oil recommendations. If you want to use synthetic oil and your car is still under warranty, check with your local dealer before switching to synthetic oil (just to make sure you're covered with the switch).

Does it work better in some cars than others?

As I stated earlier, some carmakers recommend only using synthetic oil in their engines. For instance, Chevy recommends the use of Mobil One full synthetic oil in its new generation Chevy Corvette engine. I have used synthetic oil in all of my vehicles for the last six years with great results, with one exception. I didn't use a full synthetic in my Ford Taurus 3.0 DOHC V-6. Ford specifies using a 5W20 semi-synthetic due to engine design, so I followed the manufacturer's specification. Remember, before changing to synthetic oil, check with your dealer on carmaker’s recommendations.

What are the pros and cons of using synthetic oil in my car?

Pros:

- It flows easier in cold weather, therefore no loss of prime when the oil is cold. Also, it is highly resistant to viscosity breakdown (the ability of the oil to flow easily in all temps) from heat, friction and chemical contaminants.

- Longer change intervals: 5,000 to 7,000 miles between oil changes (compared to 3,000 for regular oil). Some folks have documented up to 25,000 miles between changes. However, I would not advise going that long!

Cons:

- Costs twice as much as conventional oil per quart. However it lasts longer, so the actual cost increase is closer to 50 to 60 percent.

- Flows easily, therefore not recommend for use on high mileage engines; nor do I recommend using it in new engines during the break-in period because it is so slippery and dramatically limits the wearing of new mating parts within the engine. This initial wearing of parts is what makes for proper engine break-in, sealing of piston rings, mating of camshafts and lifters, etc.

Does it make my engine last longer?

Yes, because it's so slippery, synthetic makes for less engine wear and thus greater engine longevity.