That phrase is tossed around lightly, even by "professionals".Get proper discovery for oil tanks and such.

Or should I look into replacing with a gas or oil furnace?

That's great news for oil and gas.

make friends with a few plumbers who work in your area. they will be familiar with these types of housesHVACa lot of old houses i have walked through in southern PA are force air oil based systemsJust have them checked out to see age. none of this is badis it gas?

Some were bashing the technique saying that it doesn't work and that it is all smoke and mirrors with flawed math, while others seemed like snake-oil fanatics claiming it will pay off your loan in under 7  years and that everyone else "just doesn't understand". 

The statutory definition of securities is as follows:The term “security” means any note, stock, treasury stock, security future, security-based swap, bond, debenture, evidence of indebtedness, certificate of interest or participation in any profit-sharing agreement, collateral-trust certificate, preorganization certificate or subscription, transferable share, investment contract, voting-trust certificate, certificate of deposit for a security, fractional undivided interest in oil, gas, or other mineral rights, any put, call, straddle, option, or privilege on any security, certificate of deposit, or group or index of securities (including any interest therein or based on the value thereof), or any put, call, straddle, option, or privilege entered into on a national securities exchange relating to foreign currency, or, in general, any interest or instrument commonly known as a “security”, or any certificate of interest or participation in, temporary or interim certificate for, receipt for, guarantee of, or warrant or right to subscribe to or purchase, any of the foregoing.

I have a full time job in Oil & Gas and am investing in real estate on the side. 

I've got a demanding full-time job at a startup and am burning the midnight oil listening to BP podcasts, scouring Redfin and Zillow and talking to anyone who knows anything about the Los Angeles market.

Is it an oil fired system? 

Hi BP,I'm looking at a HUD property with BURIED OIL TANK and may also need MOLD Remediation in the garage and another room.My bigger concern is potential Oil tank leaks and soil remediation that can run thousands of $s.