I'd dispute the contention that neem oil/extracts are more toxic than fatty acid-based insecticidal soaps. ANY substance, organic or not, can be toxic if applied in great enough concentrations. Neem has been used as an herbal remedy and dietary supplement by populations in its natural locale for centuries with documented beneficial effects. The big advantage to neem oil over other organic controls is its adaptability for numerous purposes, as both an insecticide and fungicide and as an effective control of other disease pathogens. There is a very scholarly article on the pros and cons of neem oil/extracts available online, however it requires membership to the site or payment to download and view. A google search with the key words "neem oil, harmful side effects" should turn it up. Otherwise the attached is a good, well-rounded treatise on this organic control. Here is a link that might be useful: Neem oil

Your best bet is to have your burner service/ cleaning done by one guy and then buy your fuel cash from who is cheapest. It's all the same fuel, anyone telling you different is full of it. The fuel quality will exceed anything a home furnace will require and more often than not it's all coming from the same supplier/fuel terminal for a given area. A tip for trouble-free burner operation is to have two filters in the line and one of them JUST before the burner. be sure you watch the person doing the burner service and cleaning, ask a few questions about what he's doing (but don't get in his way or become annoying) and make sure he's doing everything you paid him for. More often than not, the companies who have customers sign service contracts don't properly service the furnace; this is VERY common. keep the two separate and find a good burner service guy and you'll be better off.

You should be able to keep your oil furnace and do exactly what you want to do. Maybe there is more money in it for the HVAC guy to replace everything. Need more quotes from other HVAC comapanies. "Also, if the line set is to run 50 or 60 feet from furnace to condenser, is that anything to be concerned about?" - The suction line size will probably have to be increased to 1 1/8" diameter or per the condenser manufacturer's instrucions for line size versus line length. Post model#s of condenser and a/c coil, and I can verify sizing and system performance. Good luck to you.

The flash point of vegetable cooking oil is around 600F. That is the temperature at which oil will start to vaporize, and the vapor can be ignited by a flame. A natural gas flame is about 3,000F. So, leave a pan of vegetable oil on a high burner flame long enough, and the pan bottom will get to 600F, ignitable vapors will come off the oil, and if those vapors get exposed to burner flame, you have ignition. I guess the water on the broccoli spattered, throwing a bit of oil beyond the pan, and that oil was at the flash point. The good thing is, at the flash point the oil itself isn't burning, just the vapors, so it isn't a long lived fire - get the pan away from the burner, turn off the burner, or contain the vapors with the lid. (You understand, I haven't started lots of fires in my kitchen just to test this - that's just based on the couple of oil flareups I've had plus info on flash point of different oils.)