Oil light mazda

Now follow this advice to the letter ,go to spares shop and buy a nice big tin of STP oil additive ,use a funney in the oil filler to add the additive and leave the can to drain overnight as its very thick ,no slick stuff or a graphite additive just STP then as the light will stay off for a while you trade the car in quick .

I suggest having a mechanical gauge installed just to make sure the engine has good pressure.

Check/confirm the following (on 1987 models the wire harness in the engine bay is a known defect and the insulation is very prone to premature failure):
1) Oil level/condition/type of oil (15W40 is the general specified oil for these cars). To rule out low engine oil pressure have the system pressure checked by an accurate gauge installed in place of the oil pressure switch. The switch itself is screwed into the block, bottom left side if you are looking at the engine from under the hood (on the exhaust side). The sensor is indeed a switch - spring-loaded and normally closed (open when there is pressure).
2) The oil pressure switch wire is run around the front of the engine, secured by a sheath and clips. Check to ensure the insulation of the wire is intact and not chafing anywhere - trace it out carefully. It's a one-wire design, grounded by the threads of the sensor into the block. A good test is to disconnect the wire at the sensor and drive the car. If the light is still flickering, you have an intermittent short.
3) If the oil level is normal, its condition is good and of the correct weight, it is entirely possible that the oil pump strainer is clogged. This results in low oil pressure. The other possibility is that the oil pressure relief valve in the oil pump is sticking open. In either instance (provided they are true), the oil pump should be cleaned or replaced - something that is a formidable job as removal of the oil pan involves either pulling the engine or dropping out the subframe and related components. Do not use engine oil flush treatments - they tend to overload the oil filter and cause the oil pump pressure relief valve to open and could lead to serious engine damage.

These are the usual things I would check first before condemning the engine. Loss of power, rough running and metallic knocking/thumping sounds would point towards an engine rebuild, especially if they are all present at the same time. But if the engine is running well and quietly, the turbo spools and is also quiet, then start with the aforementioned electrical tests of the oil pressure sensor switch and go from there.

Of course it can be low of oil, but I assume you checked the oil level. It can be a bad oil pressure sending unit. Check the wiring at the oil pressure sensor and make sure it is connected tight and is not loose. If you see any oil leaking from the sensor replace it. If this started after an oil change remove the filter and install a Purolator, Wix, or Mazda filter. Then check the oil level after starting and running the engine for a couple of minutes. Top it off with the correct weight oil. If it is overfull of oil it can cause the pressure light to flicker. Make sure it is not overfull. If so, drain out any excess oil. Overfilling is just as bad as under filling. Also make sure you are using the correct weight oil which is more than likely 5w20. Check your owner's manual to be sure. I would suspect you will find the oil pressure sensor is the culprit.

this is a light that indicates low oil pressure or low level, 1st check the oil level in the engine when it is hot, if that is ok you will need to have the oil oil pressure tested with a specail mechanical test gauge, don't wait on this, low engine oil pressure or level can quickly lead to engine failure, have a shop check this ASAP if level is ok and light still comes on.