Synthetic engine oil typically costs 2 to 4 times as much as conventional mineral oil, but it is definitely cheaper than an engine or a vehicle. The US military exclusively uses synthetic oil in all aircraft and the space shuttle. Aircraft manufacturers exclusively require synthetic oil in civilian jet turbine engines on airliners. GM sprung for synthetic oil in the LT1 Corvette when deletion of the C4's sump oil-cooler resulted in oil temperatures higher than The General liked with conventional mineral oil. GM mandated synthetic oil in the twin-turbo Calloway Corvette supercar with its Chevy-dealer warranty. When it really matters if an engine lives or dies under harsh conditions, synthetic oil is the way to go.

The question on most people's lips is "How much power will a performance engine gain with synthetic oil," when they should be asking, "How long will my engine last?"

Some dyno tests seem to indicate that changing to synthetic motor oil can actually add a few horsepower (see sidebar). But there are many ways of picking up a few horses. How many horsepower tricks make your engine more reliable?

We're planning to create a few "harsh conditions" of our own in the upcoming GMHTP Magnum TPI Firebird project. We'll be making some serious horsepower in the 396-inch Firebird, and we're so confident of the value of synthetics, we'll be using synthetic lubricants from Royal Purple everywhere from the crankcase to the rear axle. Our attitude is, when you're exploring the ragged-edge of street power, synthetic oil could make all the difference. When a big-buck engine is at stake, synthetics are actually dirt-cheap.

Synthetics are not controversial: "Synthetic oils do lubricate better," says AAA's web site. "If your vehicle is subject to extreme conditions such as sustained high speeds or high loads, extremely dusty conditions, racing, towing, use of a turbocharger, etc., the use of a conventional oil may not adequately protect your engine. If you are putting a lot of stress on your oil you might consider a change to synthetic oil and staying with a short change interval."

Exactly our plan with Magnum TPI.

Synthetics Oil: The BasicsSynthetics are not new. Synthetic engine oils were first mass-produced by the German chemical industry for the 1941-42 Nazi Blitzkrieg in Russia when petroleum was scarce and winter temperatures were so frigid that Panzer engines running ordinary crankcase oil had to be heated with an open flame under the oil pan prior to starting (or run almost continuously) to prevent the oil from congealing into a tar-like sludge that could prevent the engine from cranking (see History sidebar).

In the US, synthetics were designed for military tactical/combat fleets in wide-temperature operations. Mil-spec synthetic lubricants were successful and they have been used on military vehicles and aircraft (including the space shuttle) since the 1960s. Synthetic lubricants help Uncle Sam's engines survive cold starts under harsh low-temperature conditions with less wear. They help military engines survive long oil change intervals in combat conditions. In an emergency, they can enable engines to survive with critically low levels of coolant or crankcase oil.

The base stock for engine oils consists of medium-size hydrocarbon molecules in the range of 25-40 carbon molecules, which are not too thick or too thin and can be pumped under high pressure between moving metal surfaces of an engine to provide a slippery "thick film" that prevents metal-to-metal contact and all but eliminates friction. Conventional mineral oils are physically separated by distillation from the stew of various hydrocarbon molecules and impurities in crude oil. The end result is that mineral oils themselves consist of dozens of varied medium-weight hydrocarbons plus contaminants.