Changing from synthetic oil to regular oil

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2010 Mazda CX-9 Grand Touring
I've been using synthetic oil for about 7 years on my 2010 CX-9, I had the oil changed with normal oil about 4 weeks ago and now my oil light flashes when the vehicle has been driven about 3 miles or more. I checked my oil level and it is fine. Is this because of the oil change or is it a bad oil pressure switch?
 
There is no harm by changing the type of oil. Find out why the light flashes.

Does that 2010 have a simple oil pressure sensor that activates the light? If so it might be a bad sensor or it might be trouble inside the filter they put on or a problem in the engine's oil system. The type of oil had nothing to do with this. A shop can install a temporary real pressure gauge to confirm the actual oil pressure.
 
I've been using synthetic oil for about 7 years on my 2010 CX-9, I had the oil changed with normal oil about 4 weeks ago and now my oil light flashes when the vehicle has been driven about 3 miles or more. I checked my oil level and it is fine. Is this because of the oil change or is it a bad oil pressure switch?

You need to get a mechanical oil pressure gauge and get a real reading on the pressure. Hopefully it is just a bad sending unit, that would be the best case.

I would do this sooner rather than later. The "idiot light" usually comes on when the pressure is really low.
 
The engine doesn't know that you aren't running synthetic, so you most likely have a bad sensor or switch. A bad sensor or switch will cause the light to flicker or stay on.
 
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