My oil burner will not go on until the water temperature reaches 130 or 140 deg. And my high is 180 deg and my low is 160 deg. Is the honeywell aquasat relay or the room temperature thermostat located on the wall a probable cause? If not, any other suggestions as to what the problem may be?

It is designed to not turn on until a sepcific temp is met. This is user adjustable but you do not want the water to cold because that can cause dcondensation. Sounds like your system is working OK> BTW what you are talking about is the differential between the settings and this is normal. Other wise the burner would come off and on every minute.