Oil pressure light coming on at idle

Also, what type of engine oil are you using?

We've only had the car for about 4 months not driving every day but not sitting and the PO said he did an oil change a month or so before selling it to us, so idk what kind/weight of oil is in it now but we need to change it soon. Ill get the mileage tomorrow got busier than expected tonight so never had time to fiddle with the car.

And thanks for the links, I searched low oil pressure but didn't come up with anything that answered my problem in the first page. Probably wont be able to get a mechanical gauge tomorrow being a holiday but maybe Tuesday. Hell, I've got one sitting in my TR7 that's not finished yet so if I really needed to I could take it out of that, but it would never go back so I don't really want to do that...

Thanks for all the suggestions.