WTF do you mean rubbish. So if he had a 2007 Camray 5, in perfect nic on a fully pumped system with latest controls, Part L cylinder and bunded tank, you suggest it's taken out just to accommodate gas, the price of which is rising just as fast as any other fuel. As stated, if it's in need of change (which now we know it is) then he should use the gas supply.
Have you lived with an oil boiler?
Only change the boiler which he could sell off with the oil tank easily.
I had oil for 17 years, firstly an old Perkins through the wall design and then a Trianco Eurostar. Unfortunately the village where I lived had no gas and BG stated they would never pipe up the village because there weren't enough customers to pay for it!
It was a right PITA right from the start. You could never get a reliable technician to service and repair it and some of the monkeys that said they could should have been shot on the farm where they belonged.
As for fuel prices it was an absolute minefield. It varied throughout the year and was always highest when you happened to have forgotten and run out. Quite why the big gas and elec companies haven't twigged the enormous heating oil market out in the sticks is beyond me. They have enormous buying power, particularly those with there own generating capacity, but the have completely ignored the opportunity IMHO.
The only good thing about it was that when I was made redundant from my engineering job I retrained as a service engineer, took all the manufacturers' courses and OTFEC certification and it kept me going until retirement. I even met a PHD scientist who did the same because he couldn't get anyone to use their brains in system design and boiler fault analysis.
Needless to say I now live in a house with gas heating and it is absolute bliss in comparison! Best move I ever made.