METRIC OR SAE?

There are two different types of fasteners used on vehicles today, metric and SAE. While SAE is actually the abbreviation for Society of Automotive Engineers, it is the common term frequently used to describe U.S. standard or fractional fasteners.

Deciding whether you needed metric or SAE tools did not use to be a problem. Years ago, American made vehicles used SAE fasteners, and import vehicles used metric. These days with components for American vehicles being engineered in various places using both SAE and Metric measurements you may find your domestic vehicle has both types of fasteners used. If you own an import vehicle, more than likely you'll need metric tools. Likewise, if you have a late-model American vehicle, you might need some, or all metric tools.

Common metric fasteners and the wrench size required are listed in the following chart.

Before you buy any tools, check with your dealer to determine just what kind of fasteners your vehicle has. Some American vehicles are metric, while some are part metric and part SAE. Also, keep in mind that some import vehicles (such as Volvo) utilize some SAE fasteners.

While there are some points of interchange between the metric and inch sizes, it's not a good idea to use metric wrenches on SAE fasteners and vice versa. In an emergency, you can use anything that will fit, but prolonged use will only ruin the fastener.