The oil light in my 2010 Ford Territory is coming on and off after I drove through water

With the recent flooding across so much of Australia, there's a serious push by the government to convince people that they shouldn't drive through floodwater of any depth, let alone water that is a deep as the patch you've tackled.

The first thing to do is not drive the car any further. If there really is an oil pressure or level problem, permanent damage may already have been done. This needs to be checked by a workshop. However, since you seem to have already driven the car with the oil light flashing, here's the reality.

If the car still runs and drives as it did before, it's unlikely that the water has damaged the engine per se. The problem is more likely to involve the pressure of the water damaging a sensor or switch (or the wiring associated with it) that is designed to warn you of low oil pressure or low oil level. If the engine is running properly and there's oil on the dipstick, the next thing to do is have the vehicle scanned which should throw up a fault code that will lead you to the cause of the problem.

Floodwater is terrible stuff. It's full of silt and contaminants and as well as damaging an engine that ingests it, it can also destroy the gearbox or differential (by entering through the breather) and ruin electronics if it gets inside the cabin. The silt content can even act as an abrasive and wear out wheel bearings in short order.

That said, you could have a legitimate oil-pressure problem that happened to coincide with the water crossing. Stranger things have happened. A scan is the answer.