My Kubota in a 773 seems to be making oil. I'm not familiar with this style injector pump. It starts and runs fine so the pump can't be leaking a lot, or does the fuel cam run in fuel and there is a seal at the front? That sounds like a big job if it is where the extra volume is coming from. Or someone may have added oil and I didn't know it.
Change the oil and see if it does it again
Need some more info. You should be able to tell if fuel is getting in the oil.
I did change the oil and am going to watch it closely. it did not seem to be thinned. No smell either.
I had the same issue with a JD tractor. I removed the injector pump and sent it off to be rebuilt. About $150. I did this on the 4th or 5th date with a lady I was dating. We are married now.