Nissan Patrol 4x4 (Africa)

My 1994 4.2TD Patrol has started to use a bit more oil than before. No oil leaks that I have noticed; no black or white smoke from the exhaust; oil pressure and water temperature appear to within normal bounds.

The only thing I can think of is that the weather has been in the 40's here in Ukraine of late and I have been doing a fair bit of off-roading in the heat. So I am wondering whether my engine is using more oil in the squirters or blowing it out the PCV valve or something.

So I hope that I am just paranoid; but does anyone have other ideas?

What oil grade do you use? I assume due to the different extreames of temperatures between winter and summer, the viscosity of the oil may be too thin in summer when working the motor. What about valve stem seals being worn, and slowly using up a little oil at a time. I might be wrong, as I'm no expert regarding this.

10W-40, so it is not too thin.

I will keep an eye on oil levels. No need to hasten a rebuild, even if it is going to happen.