2 out of 2 members found this post helpful.
Simpler to just pump it full of pink RV antifreeze (available at Academy) till pink water starts pouring out the exhaust. I use a cheapo on/off bilge pump with a 5 foot piece of waterhose fitted to it.
Submerge the pump in pink anti-freeze (I cut out the side of a gallon jug, laid on it's side it holds 1 gallon of the pink stuff). Hook the hose to the flush port on your jetpump, start the engine then turn on the bilge pump (I lengthened it's power leads to 6 feet so they can reach the battery in my RXT). Let it pump the anti-freeze in while the engine is idling. I used 2 gallons of the pink stuff in mine, it had pink water coming out the jet pump the overflow and out the exhaust. When you run out of anti-freeze kill the engine and then turn off the bilge pump and that's that.
Also be sure to fog your engine, both while it's running with the antifreeze pumping and then again after you shut it off pull the plugs and spray storage/fogging oil in each cylinder for like 30 seconds then put the plugs back in and crank 20-30 seconds while holding WOT to keep it from starting... this coats the pistons, rings and cylinders with the storage/fogging oil fluid.
The entire process takes a little less than 30 minutes start to finish. Do remember to charge your battery every month it's in storage or plug in a Battery Tender charger full time otherwise your battery will suffer and may even die a horrible low-voltage frozen death.