Leak in copper oil pipe embedded in concrete

It sounds like you bought an old house with an old and less than ideal copper oil tube which has failed. You had the house inspected and decided to buy it in this condition.

Now that the house you bought has sprung an expensive oil leak, you are looking blame the oil company because they have delivered oil and perhaps serviced your boiler? Am I missing something? Did the oil company install the tubing under your slab? Did they break the tube or drill a hole in it? You own the tank, tubing and boiler, correct?

Unless your oil company claimed to have x-ray vision and gave you a written guarantee that it was good to go, I am not sure what you are thinking....

Well...
Code does require an oil safety valve to prevent this very situation in a gravity supplied system. The legal question is going to be are you in a location where this may or may not have been grandfathered in. Or was any oil service tech/company who saw this required to immediately notify you of it and recommend a replacement.

For example, if you were in MA, the oil line would've been replaced with a jacketed oil line and an OSV. A form would've been filled out and sent to the AHJ Fire Marshall.

Also, if your home was inspected by a license home inspector and/or any local officials, they also 'should have known' (infamous legal jargon).

So sadly for the incompetents in the industry, your attorney will be able to get you what you need.

Also, the oil company's insurance company should be notified as they will have something to say too, and obviously would be brought into any legal action.

I've had 2 fairly serious ones.
-Delivery to auto fill house who removed oil tank, left fill/vent, switched to gas and didn't notify anyone.
-Oil line froze cracked outside, but oil ran down foundation and onto basement floor.
Both cases I called the insurance company immediately.

First one, insurance paid to remedy. 11 gallons of oil, $45000.
The second one the homeowner was on the hook because if the oil tank was in the basement, they would've covered it, but outside the home, they were suppose to get a supplemental insurance for it and didn't. Even though the oil was in the basement, they had to clean it up themselves.

Best, cheapest, fastest remedy is to call the oil company and ask them to call their insurance company to clean it up. If they refuse, tell them you'll have to get a lawyer. If they are smart they will realize your way is going to cost them 10x the price over having them do it themselves or thru their insurance.

Most large oil companies are self insured up to $1 mil just for these types of issues to avoid using their insurance company and driving up their rates. Also they can move fast (as they should with oil spills) before it becomes a major expensive mess.

Had a similar incident. How does an oil safety valve work?

Because of the fuel pump cut off (and solenoids) oil lines stay purged. Otherwise, you'd have to bleed it everytime you needed it to run, especially on a lift job. Which is why some people like 2 pipe systems, but I don't and think they could lead to disaster.

Oil safety valve only works on the portion of the fuel delivery system that is delivered by gravity. It's pulled open by the vacuum of the fuel pump, otherwise it's closed. Any leak downstream and it would (should) close preventing the tank from emptying. They serve no purpose on a lift job.

They are also used as a PRV when you have a tank much higher than the burner and the static inlet pressure on the fuel unit (measured with a gauge) is over 3 psi (to protect the seals)

So how would you know you had a leak? Well on a single line system, your fuel pump would get air bound (via a vacuum leak) and the burner would shut off on safety. Nothing is leaking because when running you're pulling a vacuum (with air in this case), and when you're not running, the valve is shut, holding the oil in suspension (finger over the straw).
A proper diagnosis of a vacuum leak on the oil line would confirm your oil line is damaged.

Of course you do have some leakage, but not gallons, or hundreds of gallons.

The only problem is the manufacturer want's them installed after the fuel filter(s) for obvious reasons. So from your tank to the valve is unprotected on a gravity system, and from the OSV to the burner is protected.

From the article you linked:
Homeowners must do their part. Every property owner of a one to four family residence must either replace his oil line in a non-metallic sleeve, or upgrade the line through the use of an oil safety valve. If the entire tank and line are below the pump nothing (lift job) has to be done, but those jobs are very rare.

I referenced MA and oil lines in my first post.

No one knows more about fuel pumps and all things oil burners than George.