I was given 6 gallon of paraffin and 2 heaters last year they done a good job BUT as it was new to me i found the setting the wick to the right height so as not to burn out or smoke the green house out was an issue at 1st ::)
Not sure if I'm going to use it this year as paraffin is £6 per 4 litre bottle here.
Been give a full bottle of gas so may try that then work out which is cheapest to run