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Oil/air Separator

A device used to prevent the aeration of oil.

Olefins

A gasoline component resulting from several refining processes. Examples are ethylene, propylene, butylene. Olefins often contribute to the formation of gum and deposits in engines and the induction system.

OLV

Overfill limiting valve.

Omega

The lat letter of the Greek alphabet; a symbol for ohm, the unit for electrical resistance.

Omnibus

The origin of "bus," from the French term voiture omnibus, or "carriage for all.".

On A Pass

Making a good, fast run in drag racing.

On The Bubble

The last position on the grid subject to be bumped if another driver achieves a better qualifying speed.

On The Cam

The operation of an engine at its most efficient rpm.

On The Grid

The starting position of a race. Also known as on the line.

On The Line

Same as on the grid.

On The Piano

A term used when something is misplaced.

On The Wood

An accelerator pedal pressed to the floor.

On-Demand Test

A Ford self-test The Key On/Engine Off and Engine Running Positions which are technician initiated, are from a program within the processor.

On-Line Automotive Service Information System (OASIS)

A computerized information system for service technicians.

On-road

Refers to paved or smooth-graded surface terrain on which a tractor/trailer will operate; generally considered to be part of the public highway system.

Onboard Computer

A resident computer in a vehicle, such as an automobile.

Onboard Diagnostics (OBD)

A special, standardized diagnostic software and hardware system used to detect performance problems that adversely affect emissions and engine performance.

Onboard Fire-extinguishing System

A fire-extinguishing system permanently installed in the driver's compartment of a vehicle; required by most race-sanctioning bodies.

One Off

A custom-built vehicle with no plans for mass production.

One-piece Oil Ring

An oil ring having the expander and rails combined in a single part.