Originally Posted by YesTAM
In other words, if the POH says that the G limit is -0.0 G, it says it for a reason.
Is the limit 0.0 G though?
The Pitts S2A has an inverted oil system. It runs indefinitely right way up, and runs indefinitely upside down, but put it on a knife edge (to the left I think) or do a nice vertical line and you may find the engine losing oil pressure.
The POH G limits aren't the be all and end all, a bit of common sense is sometimes required and a look at the oil pressure gauge wouldn't go astray when doing something out of the ordinary.