Thanks for all the suggestions guys.
I finally got my report back from Blackstone. There's signs of coolant in the oil, but what puzzles me is that there's no water, and I am definitely losing both. For the past few months I've been adding just water to make up for the loss of coolant, but none of it is in the oil. So where is it going? There's no dripping, as far as I can tell, so I'm confused to say the least.
I considered that in the past there was a leak that contaminated the oil and the previous owner fixed it but didn't change oil (or didn't do it properly and there's still contaminants in the oil). That would explain why there's no water in the oil. I'm only taking short trips, so there's no time for the water to evaporate from the oil, and I have no foaming on the oil cap.
Anyway, I'll change the oil and will take it from there.
Thanks and have a great day,
Tudor