The first thing to find out is whether the existing paint is oil or latex.Unless when you said it had never been painted because the house is brand new.

As for oil tanks those can be costly and challenging if they are leaking as the soil conservation must get involved.

Like a oil town or Detroit with the automakers

It collects oils and stains like a sponge. 

If the smell is really bad and there's a chance of pet urine or other really strong odors, when you paint consider using a shellac (oil-based) primer first, at least on the floors (before re-carpeting) and up part of the walls.We bought our current home from someone who let their cats "go" wherever they wanted (it was nasty).  

The thing was a lemon and turned out to be...that's right a Ryobi.

Have you tried the peppermint oil, Dave?

Replacing the old windows with New triple pane windows, converting the oil heat system to electric. adding some mini-splits with heat/Ac capability.

I just made a post elsewhere where I warned about what I believe to be a potential downturn in 5-10 years in our market because oil and gas is taking a turn for the worst with a push for green energy.