If you own a new, or fairly new vehicle, to keep your warranty valid you must use an oil that meets the manufacturer's specifications. Virtually all well known motor oils  exceed warranty requirements for US, European, and Japanese motorcycles. But what about the other letters and symbols you find on the bottle, such as API, SJ, SH, CF, CG-4? Or SAE 5W-30?

API stands for the American Petroleum Institute, which publish standards high quality oils must meet.

SJ was adopted in 1996 and covers oils used in gasoline engines in current and earlier passenger cars, sport utility vehicles, vans and light trucks operated under vehicle manufacturers' recommended maintenance procedures. SJ oils may be used where SH and earlier categories have been recommended.

SH applies to gasoline engines in cars, vans and light trucks and indicates that the oil provides improved control of engine deposits, oil oxidization, and engine wear compared to earlier oils. It also provides protection against rust and corrosion.

CF was adopted in 1994 for use in indirect injected off-road diesel engines that use a broad range of fuels, including those with a high sulfur content. It offers effective control of piston deposits, wear and corrosion of the copper-coated bearings used in this type of engine.

CF-2 is formulated for use in two-stroke diesel engines requiring highly effective control over cylinder and ring-face scuffing and deposits.

CF-4 covers oils for use in high-speed, four-stroke diesel engines. They are designed for use in on-highway, heavy-duty truck applications.

CG-4 describes oils for use in high-speed, four-stroke diesel engines, and is suitable for both highway and off-road applications. They provide effective control of high temperature piston deposits, wear, corrosion, foaming, oxidation stability and soot accumulation. These oils are especially effective in engines required to meet 1994 emission standards.

SAE stands for Society of Automotive Engineers. Motor oils have SAE grades, or numbers that indicate viscosity. In other words, the SAE numbers tell you the "thickness" of the oil. The lower the number, the "thinner" the oil.

W signifies its winter rating, showing that it will perform well in particularly cold weather.

When you buy oil, or have it changed, be sure not only to pick the right API rating for your engine, but ask for the SAE viscosity recommended in your owner's manual. Normally, manufacturers recommend multi-viscosity grades, which are suitable for use over a wide temperature range.

Today, motorcycle manufacturers usually specify SAE 20W-50 oil. This will give excellent protection in virtually all parts of the US.