The property is a 3 bedroom house that is approximately 1800 SF. the oil tank is 300 gallons and would lobe tp hear from other property owners that have this type of furnace.

I'm a private landlord and I don't have office hours.Fun fact, how many gallons of used motor oil can a tenant collect in random open and closed containers in 2 years?

Solution: we installed a 2,000 gallon cistern with a float sensor.

My mentor in multifamily once told me the first thing he does when buying a building is change the toilets to one's with smaller tanks. calculate what water costs per gallon.

Fifty gallon concrete pots with agave/ bouganvilla/ thorny hawthorn/ firethorn/ thorny simlax (invasive maybe not allowed in your location) cactus/ corona de maria/ blackberry/ big spikey plants with a sign that says you are filming anyone who trespasses on the lanai and is being broadcast on youtube. 

It emptied a 5 gallon bucket of primer in about 40 minutes.  

I have about 2 gallons of neon orange paint I'll mail to you if you provide a compliant shipping label ;)I'll trade your shake for a beer, we still can get those right?

Then decide if him doing 50 loads of wash a year, maybe 1000 gallons of water is worth losing a good tenant.

So those that live in California and the north east you basically get one gallon of milk and a slice of bread.

looks like the guy underbid this and is now trying to split it with you. i mean, it's only $1k more. those extra 15 gallons (if true) of SW aren't cheap. if you liked the job they did and how they went about it, i'd just pay them what they're asking and move on.