Here’s a 'neat' (literally) way to change engine oil using an old propane tank. You can get these for nothing since the older ones are now illegal. One of your engines (with twins, or a nearby car or truck) is used as a vacuum pump. I use the PVC fitting on the carb for my vacuum source. A 'Tee fitting' in the tank allows air to exit while oil flows to the bottom of the tank through a length of pipe. All you need is a few common fittings, some ¼ inch steel brake tube (that you poke down the oil checking tube hole) and some 3/8 inch hoses for vacuum and oil. You’ll need to unscrew the dipstick fitting at the block to get the tubing down into the oil pan. I also use this rig to suck the oil out of the old filter before disposing of it, avoiding another mess.