MF35, Engine Oil Pressure Question

I've followed the oil change schedule suggested in the manual using the recommended oil - think it was 5W20 - maybe 5W30...I'm writing this from work, not home, and don't remember.

Recently I've noticed that the oil pressure shown on the gauge starts off at about mid-range in the Normal range, but as it warms, it drops to just barely into the low end of Normal. I would expect it to drop as the temp goes up and oil thins, but since it is so close to the bottom of the normal range, I've been a little concerned.

Is this a concern, and if so, does it just suggest using a higher viscosity oil in the summer, or other problems? Temps around here have been running in the 90s up to a little over a hundred. The temp gauge says the engine coolant is running mid to high normal, but not high enough to be concerned.

Thanks!

The MF35 diesel manual says...
30W above 90-deg temp
20W or 20/20W at 32-90 deg
10W at 10 deg
5W or 5W/20 at -10 deg.

I asked the question on this site when I first got the tractor, and if I recall, the reason I'm using what I am is because that's what I was told by somebody on this site.

I've only changed oil once, at 100 hrs and am coming up on the next change now - haven't had the tractor that long and don't use it as much as if I was full time farming. My practice is always to change the filkter with each oil change, and at least in my cars and trucks, I usualyy use the better grade of Fram filter. Can anybody give me a Fram number for the MF35 diesel with spin-on adapter?

My inclination was to stick with Castrol 30W. Our temps here run 90-100 deg most of the summer with occasional to 110 deg. In the winter, it's typically 20-40 deg, but I've seen up to a few days running at -25 deg, but that's only happened twice that I remember since the late 60s, and not being a full time farmer, not likely I'd choose to be out working in that weather, and I expect to have the tractor in a barn come winter.

Bottom line - other than oil weight, sounds like I'm doing it about right. I'll switch to 30W and stick with it.

• Shell Rotella