Oil light coming on 2008 Tribute
 

Just recently the oil warning light has been coming on on my 2008 Mazda Tribute. It only comes on when I come to a stop and the engine is idling. Not sure if it is a sensor or maybe the oil pump going out.

Assuming your oil is the right level and grade you need to either swap out the sensor or test the pressure with a known good shop gauge to find whether you have a real oil pressure problem or not.

Normal sensors trigger at VERY low pressure so you need to do it fairly urgently - does the engine knock or rumble under idle or load?

No the car doesn't knock or rumble at idle, the strange thing is today the light never came on

Quickest is to inspect the wiring as a short or break can give this problem, then swap the sensor if one is available easily...or as I said, get a shop gauge put on it to see what the pressure really is.

Good sign there is no rumble.

Also how old is the oil if it starts to break down when hot it thins out and is not pumped around with as much pressure
I have used cheaper oil a couple of times. and had to do oil changes more frequently I now do mine every 5000 kms along with the oil filter for about $50, it is cheap insurance.
To get at the oil pressure switch you need to lower the air-conditioning compressor as the switch is directly above this

I just changed the oil couple days, and had same problem when comes to a stop, the engine is rumble under idle, but did not happen before oil change, I think with the engine over 300K suits to use the oil thicker like 10W/40 or so, but the guys at Auto part gave me 5W-30, I had other engine spare swapped switch, but problem still remain....will try thicker oil today.....hope it gone

Try something like Castrol GTX 15w40.

Is that at a synthetic oil or should I even consider using synthetic in the Tribute

Depending on your market, there is a Multigrade Mineral & a synthetic version.