The other questions for us is where will we store extra bottles? We can only fit out 4.5 kg bottle in our gas locker, which is essential because our gas connector, regulator etc is in this locker. Besides we don't want to have a gas bottle in use that is not in the locker for safety reasons.
Few will argue, you don't actually need much gas as eating out in Asia really cheap. But still we like to have a cuppa, not every single meal is eaten out and we like to bake.
We have read Indonesia and Malaysia have the same fittings and Thailand has the same fittings as in Australia and most marina's will fill your gas cylinder. (at the time of writing I am unsure about Singapore). You can not exchange bottles from one country to the next and you cant get them refilled.
Seems most cruisers who are there now are buying bottles in each country (not expensive) and working around the refilling that way.
Matilda carries 2 x 4.5 kg aluminium gas cylinders, each lasting us about 3 weeks. We do not have a generator on board for heating water. At the time of writing we are putting into place strategies to extend the life of the gas tanks. Friends of ours are very gas conscious (also doing the Darwin Rally) they wash all their dishes in salt water first and they wash their bodies in salt and rinse both dishes and bodies off with 1/2 a liter of fresh water. Its not essential to wash in warm water, actually the coolness of the water is a bonus when having a body wash as its so warm in Asia. We wash our dishes only once a day. We rinse all our dishes in salt water and do one load in the evening with some warm fresh water.
We have decided to buy another 9 kg gas cylinder. We are confident we can decant the 9 kg cylinder to the smaller bottles when we have to. We will have the POL fittings and 6 and 8 millimeter hose barbs and a length of pressure tubing. We also know the fitting for Indonesian gas cylinders are easily purchased once we get there. We are also, happy to purchase bottles as we travel through each country.