Been using 10-30 oil in this tractor. Has 30lbs when cold but gets down to 8-10 when warmed up. How much is enough? Oil pump issue? Would heavier wt oil help? Thanks

Nominal oil pressure is 27 PSI on a good FORED N-Series engine at idle on start up. When engine warms up and gets hotter it will drop some. When a hot engine shows 10 PSI it is a sign the engine is worn and needs a rebuild. Even less than 10 PSI more serious and should not run it at 5 or below. When engine is running at 3/4 or full throttle it will show a higher reading so always check at idle. You don't keep adding oil to the system. You fill overfill. You should get the manuals and know how to properly check capacities.

Thanks so much for the good information. Changed to 15-40 oil and it came up to 20 at a warm idle. Revved up the needle pulsates from 40 to 60. It’s a fairly new gauge so I wonder if air in the line would cause the pulsating?

No, air lien not causing the higher rate. The N's used a 0-50 PSI Oil Pressure Gauge. The 0-80 gauge came out with the larger NAA/Jubilee 134 engine. How old is the engine? when was the last time it was overhauled? That is probably your root cause problem. With engine cold, check the oil level with the dipstick. Start engine and let warm up at idle, do not rev up, for at least 15 minutes, good and hot for 30 minutes is better. Watch Gauge at idle start up, do not rev engine, and note. As engine gets hot it should start dropping a bit. If it gets to 10 PSI in a short time, engine needs a rebuild. System is worn out.

Generally if you have 10 psi for every 1000 RPM you will be fine. Yes, heavier oil will help, especially when the engine is hot. I use either 20w-50 or 15w-40 in my 9N which helps my low oil pressure. However, that's too heavy for winter if you use your tractor during the winter. I start out at 40 PSI when cold and end up with 15 PSI when warmed up. In most cases, it's worn out main bearings causing the low pressure.

Thanks so much for the good information. Changed to 15-40 oil and it came up to 20 at a warm idle. Revved up the needle pulsates from 40 to 60. It’s a fairly new gauge so I wonder if air in the line would cause the pulsating?

WAG - pulsating at 40-60 is the oil pressure relief cycling. I think it cracks around 50.

You got good pressure - be happy.

TOH