The oil pressure switch is quite easy to replace (I think) and as far as I am aware I don't actually have a low oil level light on my Zafira B 2010. I do have an oil pressure light and that could come on if my oil level is low resulting in low oild pressure. It could also come on if the oil pressure senser is faulty or intermitant. This could result in an intermitant oil light. To be honest I would take it to a reputable mechanic, not saying his mechanic wasn't reputable. In fact I think he made a sensible suggestion.

 

The indicator is the oil level (https://1drv.ms/i/s!AkpCntm7XIBuhM04A_b9eD5P4lvQPw), or at least that's what it says in the manual

However I went for a ride (first since I got it!) and noticed the light came up once the engine was well warm, i.e after more than 5 miles. This gave me a hint so I remembered I hadn't checked the coolant reservoir (I know, I should have done it before buying it!): https://1drv.ms/i/s!AkpCntm7XIBuhM00PG6cG-MuO4QCUQ

Bother.

I'm going to take it to the local garage for a flush ASAP: the engine is not overheating, the oil is clean and the neither oil not water levels have changed in ~200 miles, so there's hope it's not the head gasket.

 

Common issues on these is the oil cooler. Look up behind the exhaust manifold for an oil leak. It normally drips onto the exhaust just before the flexi pipe.

Not sure why it would bring your oil level light on. Am assuming the level is OK on the dipstick?

 

Common issues on these is the oil cooler. Look up behind the exhaust manifold for an oil leak. It normally drips onto the exhaust just before the flexi pipe.

Not sure why it would bring your oil level light on. Am assuming the level is OK on the dipstick?

Yep, oil level at the max and hasn't changed since I got it. Oil's clean too. I'll take a look at the oil cooler tonight.

 

I couldn't manage to look at the oil cooler, but last weekend the heating stopped working and the engine temperature wouldn't reach 50C, so I took it to the garage.

It turns out the oil cooler had been changed under one of the previous owners (I'm the 4th) but the mechanic didn't bother to clean the system properly, hence the sludge in the reservoir. As that wasn't enough, it seems they forced the pipes to fit, cracking the reservoir as a result (it was seeping, so changed that).

The warning light was simply the service indicator had not been reset properly - the scanner showed service done, but oil quality near 0%. Put it back to 100%, no more warning light.

And finally, the thermostat had to be changed together with the plastic housing as that was damaged.

I've found receipts for services at two garages (FSO in Luton and London Motor Centre Ltd), neither of which seem to have checked the coolant anti-freeze protection from what I can see. I'll be checking what records they have, although I won't hold my breath...