Pontiac used an oil light to warn the driver of low oil pressure just like every other maker. Right up to the last engine built, the light was set to come on at less then 5 psi (+ -) 1.5 lbs, and this was right as the oil left the filter. The 250 used the same sensors as the V8's would have used.
I have seen two "oil pumps fail", and both were due to 20-50 oil and both still had working pumps with the drive shafts sheered off.
Joe
