Gas in PR is unleaded - just like the US. The difference is that most stations only have 87 and 91 octane - 93 is rare, but growing in availability. Diesel is not available at every station, since there aren't many non-commercial diesel vehicles on PR roads - most of the sales tend to be for diesel generators. Anyway, diesel pumps in PR - just like in the US - are green and of a larger diameter.

Puma gas stations in PR are common, but have a bad reputation among local motorheads due to additives - in my case my GTI runs better on 91 from other branded gas stations than it does on 93 from Puma (in the handful of stations that offer it). I prefer Total, Toral, Ecomaxx, Gulf, Shell, etc.

To me this sounds more like a no-name gas station with an old/rotting fuel storage tank that's leaking water, which is fairly common in the country and in some coastal areas.. The catalytic converter in my old Jetta was destroyed due to this.