Had a chance to try the Ola Dubh (Black Oil) two nights ago with my Dad. From the label:

Ola Dubh (for "Black Oil") is so named because it is gloopy and viscous. This limited release has been matured in casks from Orkney's award-winning Highland Park distillery to add complementary whiskey notes to what is already an amazing brew. It is chocolaty with a roasty bittersweet aftertaste.

The 16 reserve is so named because it is aged in barrels used for making 16 year old single malt whiskey. It really does pour like viscous black oil. It had a nice aroma, and the barrel aging was readily apparent.

Personally, I like strong, deep and solid flavored beers, especially stouts. This beer started out strong, but quickly revealed a rather hollow profile with robust flavor at the start, but not much left for the middle and end. It was however a very balanced beer, with chocolate, roasted, whiskey, and malt flavors being present in nice proportions. It was quite easy to drink, and there was a significant, but not overpowering alcohol taste.

As a comparison, we also tasted one of our own 12 year old IRS (Imperial Russian Stout) beers. This finished off where the Ola Dubh started with deep full-bodied flavor that started strong, peaked in the middle, and ended with a very pleasant, firm aftertaste. Interestingly, there were some fruit flavors in our brew which really added to the complexity and the perceived quality of the beer. They gave it a richness and mild sweetness which was not matched by the Ola Dubh.

Both are good strong beers, but for those who want "black oil" to mean deep, dark, and heavy throught the flavor profile, I would recommend the Stone IRS. I think we drank the very last bottle of our own IRS, so we will have to wait another 12 years to taste that one again