Cannot say if it is the case here or whether it is even common to tractors, but generally oil pressure alarms/interlock are on time delay to suppress for a number of seconds during startup, especially for interlocks, to allow permission to start with no oil pressure until it has a chance to come up normally.Oil alarm does not come on when you first crank up and run at idle. Dip stick was a little low so I added oil up almost to top level, about qt or little more. Engine has 200hrs. It started when engine went into regen at 199.8hrs. It went thru the idle up and down series until it was finished with regen. Let it set overnight. Actually, went out and ran tractor for 10 min. at high rpm with no problem then all of sudden oil light came back on. Engine would not throttle up after that.???