when I use the breaks the oil light goes on.

[137]

I have an 86 bronco 2 and sometimes when I use the breaks, the oil light goes on. I have had the oil changed recently. Anybody know why it would do that?

[Truck]

You have a bad vacuum on the intake manifold? Reverse pressure?

http://www.hoppers.com.au/basics.htm

Maybe if your engine has 'blow-by' that the pressure could be blowing the oil backwards? (Maybe.)

Master Cylinders Make Pressure

To apply a hydraulic fluid pressure to the brake calipers, we use a master cylinder, in essence small pistons connected to your brake pedal which generates fluid “pressure” according to the force applied to it and the area of the piston by the formula.