Technical Multijet: Oil pressure warning light

[pulhamdown]

Hi. Since it`s last service, our multijet`s oil pressure warning light takes 3 or 4 seconds to go out after a cold start. If I turn off the engine immediately, and restart it, the warning light goes out before the engine fires. I suspected a faulty non return valve in the ( new ) oil filter fitted at the service, but it`s been in to the dealer and had another filter fitted - same problem. I only have his word that a new filter was fitted, but I`m wondering if anyone else has had the same problem. I doubt it`s serious, but I would like it sorted. BTW, mileage 16,000 - 56 plate
Colin

 

[KozmoNaut]

The oil pressure light will always stay on for at least a few revolutions of the engine until the oil pump has built up the correct pressure.

On my MJ, it goes out instantly in warm weather, but it takes 3-4 seconds in the current winter conditions.

The reason it goes out instantly if you shut off the engine and start it again quickly is that the pressure is still high from when the engine was running.

You should only be concerned about the oil pressure light if it stays on for more than 30 seconds or so, or if it comes on while you're driving. In the latter case, you should be VERY concerned indeed.

 

[BenP]

What oil did they put in at the service? If it's too high a viscocity when cold, the oil will be thicker and therefore take longer for the pump to build pressure.

A good example of this is the old VAG 1.8T unit. The handbook says it'll run fine on 0w-40 or 10w-40 - but from our experience cars that get filled with the latter almost always end up with oil pressure problems when cold.

Ben

 

[pulhamdown]

Thanks Ben, I suspect you`re right. The "problem" has only arisen since the service, and coincidentally the cold weather. I just need a warm day to confirm! I`m not holding my breath!
Colin

 

[BenP]

IIRC the MJ should be filled with 5w-40, and the ridiculous thing is a 10w-40 could be enough to cause these issues. Unfortunately a lot of garages now just throw 10w-40 semi-synthetic in everything without any prior consideration to anything else.

Ben