Butane or propane fir BBQ

Doesn't make much difference, but most people use butane and it's normally cheaper. 

Thank you 

Propane works better in cold temperatures. By cold, I don't mean anywhere near like we get here. If you lived up on a mountain top with snow then propane would be the better choice. Here not so much. 

Price difference is negligible but I would question butane being cheaper than propane. 15.89 for 12.5kg butane and 13.98 for propane 11kg (official Repsol prices) although, in our area, butane is easier to get hold of. 

Sounds like I'd be better with butane then. Thanks 

Check with the company if the jets in the unit can use either gasses mentioned. If not then one may purchase jets for either gasses as running it makes a huge difference. I have replied out of concern regarding a post stating its cheaper to purchase Propane, that's it. A total Bollocks reply. I am also concerned a child may be hurt. You will need to change the regulator valve as Butane (Blue bottle) and Propane (Red bottle) run at very different pressures. Also the gases run/burn/operate at lower/higher operating temperatures, this is also effected  greatly by outside ambient weather/temperature. UNDER NO CIRCUMSTANCES SWAP FROM BUTANE GAS TO PROPANE WITHOUT CHECKING THE ABOVE MENTIONED. Good evening. R. 

It says online king broil uses either.. I'm clueless re this tbh. Thanks for your helpful info. 

Hello. You have the model number and year of manufacture stamped on the unit. You can obtain the telephone number for the company online. TALK TO THEM. ITS SO SIMPLE. To reiterate the gas bottles operate at very different pressures between Butane and Propane, You will need to change the regulator valve regardless to whichever gas you use. DISCUSS THE JETS> I have made it easy for you. America. (800) 2652150 Customer Services. NB. The seals in your BBQ will not withstand the increased pressure from a Propane bottle without the correct regulator valve. Enough said. R. 

Thank you so much. Very helpful

Exactly right, ignore the scaremongering. 

Regarding the price, in practice the differing calorific values of the two gasses means that they both work out almost identically. 

An old calculation but still valid.

Calorific value of butane = 49.47 MJ/kg
In one 7kg bottle = 346.29 MJ
Cost of 7kg on Calor website on 12th March 2010 = £19.45
Cost per MJ = £0.05616

Calorific value of propane = 50.37 MJ/kg
In one 6kg bottle = 302.22 MJ
Cost of 6kg on Calor website on 12th March 2010 = £16.99
Cost per MJ = £0.05621

The difference being £0.00005.