Pressure in the lubrication system

In order for the lubrication film to withstand even the highest loads, the oil always enters the lubrication points under pressure. But too high a pressure, for example with cold and viscous oil for a long time, damages the engine. This is prevented by the overpressure valve (bypass) in the connecting flange of the oil filter. It opens at approximately 4 bar and returns oil to the suction side of the oil pump.

In technically healthy Focus engines, the oil reaches the lubrication points already at medium engine speeds at a pressure of about 1.5-2.5 bar (oil temperature is about 80-100°C; multipurpose oil SAE 10W-30). At idle, the engine needs about 0.6-1 bar. An oil pressure gauge will give you accurate information about oil pressure. The Focus doesn't have one as standard, but you can install an oil gauge relatively easily yourself.

The oil pressure indicator light only indicates insufficient pressure

You cannot demand an exact measuring value from a standard oil pressure indicator lamp, it only lights up at a pressure of 0.3-0.5 bar. In other words, the oil pressure warning light only warns when engine damage threatens: at 0.3-0.5 bar, a reliable supply of sufficient oil to the inside of the engine is no longer ensured. For example, malfunctions may already occur if your Focus goes through a corner quickly with too low an oil level, the resulting centrifugal forces displace the oil inside the crankcase towards the outside of the corner - in this situation, the oil pump delivers only hot air from the crankcase. Oil pressure inevitably drops, and engine failure can be a costly result.


If, after a quick drive on the autobahn or over a mountain pass, the oil pressure warning light flashes at idle, this is a sure sign that the oil pressure is no longer sufficient. Although while the control light goes out when you lightly press the gas pedal, there is no reason for great concern - act more carefully, «healthy» the engine cools down again during the trip.

Only if the oil pressure warning light is permanently on:

• stop immediately and turn off the engine
• check the oil level and...
• top up the missing amount as soon as possible. If not, drive carefully to the nearest gas station and fill up the oil there. Check if the control light actually goes out after this
• if not, have the vehicle towed to the nearest workshop and have a specialist determine the cause. Under certain circumstances, you can avoid serious engine damage in this way.