This seems like a silly question. Rocks in oil tank?

Azogro

Hey guys and gals, weird not traditional question here.  
Iv recently moved into a new place, and I have an old oil furnace from the 90s (ish) 
Unfortunately my tank is buried so I don't have a good way of doing a tank inspection, without a new boreoscope. 
I'm kinda chasing my tail with oil until I can actually verify that my tank isn't compromised. Etc. I'd rather not pay 500$ to find out my tank is cracked.
Finally to my real, and semi stupid question..... I keep getting lockouts due to low oil but iv still got 50+ gallons on my meter stick. I can put a few gallons in, an she'll chug along until it drops to a certain point around the 45-50 gallon mark, and then I can hear the siphon squeal of the pump drawing air, and then the lockouts start because of loss of flame. 
I either think that the draw tube got old and snapped off into the tank, or the low point is just naturally like 2 feet from the bottom of the tank. 
Would it be stupid to dump a bunch of larger gravel into the tank, to fill the dead space with something that wont break down with hydrocarbons and actually get to my oil? 
I understand with the big picture, oil is oil, so just add more, and stop worrying about the bottom of the tank, and if that's the inevitable concensus.... well I get it.... but it's seriously maddening to have this issue with such a large amount of oil on hand. 

STEVEusaPA

Yes rocks are a bad idea. For one, when the tank has to get removed, you're going to have to pay to have those contaminated rocks properly disposed.
Sometimes the draw tube just gets a pinhole at the 'runout' level. A boroscope isn't going to help.
Most jurisdictions require all underground tanks to be registered with the state, and a test shall be performed annually to make sure it isn't leaking.
Instead of worrying about rocks and dip tubes, you should seriously and sooner-than-later, get an above ground tank, preferably indoors, and get the underground tank properly abandoned. If it goes bad, it'll be real bad...i.e expensive.

Azogro

Makes enough sense. Thanks for the advice. I'll just take your word for it, and leave it alone. A few gallons of oil isn't worth the headache now or later. And it's a pretty inefficient means of heat for me. Just the easiest. 
At this point, and in my environment, it will be cheaper and simply just more sensical to convert to a heat pump. 
In all reality, I'm just doing quick aesthetic renovations, on a bunch of family homes. But this is a situation where the land out values the ancient homes by a 1000x 
It's mostly just so buyers don't have to do walk-throughs on haunted caves into the abyss.
The reality is, anyone who would buy the land, will just start from scratch.

Jamie Hall

If the "ancient" houses have no value; and it's all about the money -- a situation which, as a historian and restorer of ancient houses, makes me cringe and cry -- just bulldoze the whole show and dig up the tanks and remediate. Don't put any money into it.