Further to my last post checking the oil pressure should be more than " somewhere in the green ". Oil pressure is correlated engine RPM and with oil temp, so if the oil temp is 180 F ( or normal operating temp ) the oil pressure I would expect would be mid range in the green ( no unit markings) or around 80 PSI. Very high or very low pressure, even if in the green, should prompt a low speed reject and further investigation
The only time I have rejected a takeoff in a light SEP was due to high ( on or maybe slightly over redline). It was a checkout in an owners airplane. A cold day, very short taxi and checks done quickly but correctly did not give the oil time to warm up. This was exacerbated by the use of straight 100 oil instead of a multi grade.
Returning to the run up bay and letting the engine warm up for a few minutes resulted in a normal oil pressure reading when full power was applied