I would get rid of oil and run pretty much anything else for heat. You are very fortunate you caught the leak early.
Search on the internet for residential fuel oil clean up and it will turn your hair gray!
I saw one where they moved the house do they could excavate the oil tainted soil.
Another one where the guys neighbor had an oil tank leak and he posted a picture of an excavator in a pit in the ground about 20 feet deep and they were digging deeper. Two excavators, one way down in the pit bringing dirt up so the second excavator could grab it and dump it in a truck.
Costs were $250,000 and insurance wouldn't cover it.
At least look into double wall tanks.
Some states has very strict laws on oil tanks, some don't care. I talked to a guy that switched over to propane and he was just going to abandon his underground oil tank. The state he was in had no requirement to remove it. I told him to get it out as it was easy now. He left it in place. A few years later he tried to sell the property and disclosed the oil tank. Nobody would buy the home with the tank in place, so he hired a company to remove it. From the time he first talked to me about it, to the time he was selling the home the state changed requirements and got crazy about underground tanks. He had to hire a pro to remove it, and it had to he inspected. It cost him something like $50k by the time he got it cleaned up as there was some oil in the ground, not alot, probably just just many tiny spills over the years from the oil company when they filled the tank. If he had removed it when I told him too he might of hired an excavation company but there was no inspection, no requirements from the state. It might have cost him $1K or $2K tops. It would have been dig up the tank, toss some dirt in the hole and be done with it.
