Small Engines (Lawn Mowers, etc.): oil pressure, oil pressure gauge, briggs stratton

Question
Hi Tom ; Just a follow up comment on the oil pressure reading i have on my craftsman DLS/3500 with A 1 CYL. INTEK 20 HP Plus  fully pressurized .Model #31p977 Type#1066E1 Code#071212ZE . I installed an oil pressure gauge 0-80lbs range. After warming engine readings are as follows 5lbs.@ idle & approx. 20lbs. @ full run speed(rabbit). the engine still has factory oil with 4.3 hrs. I plan on changing the oil & filter after next cutting.Plan on using a hd 30w oil. So, next time you contact that rep. @ Briggs & Stratton you might mention the oil pressure readings are measurably higher than his quoted 9 to 13 lbs. Thank you for your response and look forward to your help in the future. Ken in Rochester NY

Answer
Ken, you also have to keep in mind, the reading Briggs gave me is right in the middle of your low end and high end readings. Different things can effect oil pressure. Examples are, oil type,temperature,Rpm's, oil condition, ambient temperatures, engine age, and engine load. What Briggs did fail to mention to me is at what RPM was their readings applied. Their quoted pressure range very well could have been done with a mid range RPM setting as the reference point. Makes sense to me to give the psi based at a safe mid range rpm. The 9-13 is almost smack dab in the middle of your readings. The other thing to take into consideration is the load the engine is under, you may get 20lbs while in the driveway at high idle and no load, keep it at that idle and start cutting 2 feet of grass and watch it drop. Those are just safe guidelines. For normal situations. Enjoy your new grass chopper Ken...........your friend,Tom