While I previously said 87 was not used, I should have mentioned the option of using post 87 for a low oil pressure warning light. The 87A in this case works as the NO line, 87 will be the opposite, it will be NC, hence when oil pressure is lost, this leg will close and energize the warning light. You can buy 1/2" very bright to install in your panel in a variety of placed.
Here are the ones I like and use...
They come in a variety of colors