| Octane |
|
| A numeric rating of gasoline’s resistance to detonation(premature ignition). The higher the octane number, the less chance of detonation. High octane (above 91) is usually worthwhile only if the manufacturer specifically recommends it. Octane is actually a hydrocarbon(C8H18).
|
|
| Off-Highway Vehicle |
|
| Vehicle intended for operation on unmade surfaces or rough terrain (i.e. for construction or agriculture).
|
|
| Oil |
|
| Engine oil comes in various ratings SAE 5W-30, 10W-30, 10W-40, etc. For example, a 10W-30 rated oil will flow like a light SAE 10-weight oil at low temperatures. The W signifies that it is a winter rated oil. The 30 designation means that at engine operating temperatures, the oil will behave like a heavier SAE 30-weight oil. Low viscosity at colder temperature allows the oil to circulate more quickly and protect vital engine parts. Higher oil viscosity at elevated temperatures prevents direct metal-to-metal contact.
|
|
| Oil Pump |
|
| An engine-driven pump that delivers oil, under pressure, to the engine`s moving parts.
|
|
| Oil Ring |
|
| The lowermost piston ring that scrapes off excess oil from the cylinder walls and returns it to the oil pan via vents in the ring and piston.
|
|
| Oil, Synthetic |
|
| Oil that is not derived from raw petroleum. Synthetic oil has superior engine protection properties compared to conventional mineral oil. Synthetic oil costs 3-5 times more than mineral oil.
|
|
| On Board Diagnostics (OBD) |
|
| a unit that monitors the Electric Control Unit and system responses for errors during normal vehicle operations. When the vehicle is serviced, this information on the errors can be down loaded and displayed to the service personnel which will facilitate the trouble shooting process. |
|
| On-Center Feel |
|
| The responsiveness and feel of the steering when the wheel is approximately centered. In a car with good on-center feel, the steering wheel tends to return to center when slightly deflected, assisting straight-line stability. |
|
| Opposite Lock |
|
| A technique in which the steering wheel is turned in the direction away from where the car is turning. Opposite lock is used to control a car when it is oversteering and its tail is swinging wide.
|
|
| Overcapacity |
|
| The situation where maximum global prodution of automobiles exceeds the total global demand for automobiles.
|
|
| Overdrive |
|
| A small auxiliary gearbox that provides an additional gear ratio. It causes the drive shaft to turn faster than the engine crankshaft or "overdrive" it. Overdrive gears are used in most modern transmissions because they reduce engine rpm and improve fuel economy at highway speeds. It is engaged manually when under way. It has a transmission ratio below 11. For instance, a manual transmission fifth gear ratio could be 0.701.
|
|
| Overhead Cam |
|
| The type of valvetrain arrangement in which the engine`s camshaft(s) is in its cylinder head(s). When the camshaft(s) is placed close to the valves, the valvetrain components can be stiffer and lighter, allowing the valves to open and close more rapidly and the engine to run at higher rpm. In a single-overhead-cam (SOHC) layout, one camshaft actuates all of the valves in a cylinder head. In a double-overhead-camshaft (DOHC) layout, one camshaft actuates the intake valves, and one camshaft operates the exhaust valves.
|
|
| Overhead Valve (OHV) |
|
| An acronym for overhead valve. This simply means that the intake and exhaust valves are above the cylinder head. SOHC engines have a single cam over the cylinder head. DOHC engines have two cams above the cylinder head. All OHC, SOHC, and DOHC engines are also OHV.
|
|
| Oversteer |
|
| A situation that occurs when the rear wheels contribute to steering the vehicle more in a given direction. This often occurs under hard braking while turning. The rear of the vehicle loses adhesion and starts to rotate in the direction of steering. Oversteer can be used to better place the vehicle coming out of a corner. Usually, oversteer is undesirable because it is difficult to control and can result in a disastrous spin. Most cars are designed not to oversteer under normal conditions.
|
|