OIL-PRESSURE LIGHT

I drive a 2017 Mahindra 2,2-litre S6 Pik Up with 6 000 km on the clock and, so far, I am very happy with it. There is only one problem I have noticed and it has to do with the oil-pressure light.

When starting the engine in the morning, the light takes about four seconds to go out. While driving the vehicle, it stays off, indicating the oil pressure is adequate. Switching off the engine after it reaches operating temperature, it takes just two to three seconds for the oil-pressure light to go off upon restart.

There are no mechanical noises from the engine – starting it cold or hot – suggesting it is getting oil pressure to critical components. The engine runs and sounds smooth while the low oil-pressure light is on. I have visited Mahindra Welkom and asked if I may start one of the new Pik Ups on the oor and the oil-pressure light behaved in a similar way.

1. Is it normal that the oil-pressure light takes four seconds to go off?

2. Will it cause any damage to the engine if the oil pressure is low for four seconds after start?

3. What prevents the engine oil from draining back to the sump? To my knowledge, it is the oil lter’s non-return valve.

4. Does oil viscosity play a role? NEELS VAN DER WESTHUIZEN Via email

The oil-pressure switch is quite a simple device, consisting of a diaphragm and spring that opens or closes an electric circuit running to the oil-pressure bulb on the instrument cluster (see Tech 101). The fact that all new Mahindra vehicles tted with the 2,2-litre engine behave in a similar fashion indicates nothing is wrong with your vehicle and you should not be concerned. Oil pressure is critical and the engineers would have considered this during development and durability testing of the unit. Modern oil technology has improved dramatically and a thin layer of oil tends to stick to the metal to prevent damage during start-up if the oil pressure is not yet suf cient, but we doubt this is the case with your Mahindra.

1. It depends on the location of the oil-pressure switch and its activation pressure. If the switch is located close to the oil-return path (in contrast to close to the oil pump), it would take some time to build pressure as a percentage of the oil does leak back to the sump over time. 2. Again, it depends on location and pressure. With modern oil technology, the risk is extremely low.

3. That is correct. A modern oil lter has a non-return valve to prevent the engine oil from leaking back to the sump.

4. Yes, oil viscosity does in uence oil pressure with generally a higher viscosity (thicker) oil leading to higher pressure. It’s best to stick to the OEM speci cation as this is what the engine is designed for.