[Vwdiesel] Cooling System Flushing

[toensing at wildblue.net]

I have been using a cooling system additive called "RME-25" which is supposed to eliminate the need to replace antifreeze by replenishing the additive in antifreeze. RME-25 instructions are to add 8 ounces every to replace the additive package in antifreeze. Has anyone heard of it or is it just sold in Calif.? How does one check antifreeze as to whether it needs to be replaced? Any comments on ethylene glycol vs. propylene glycol antifreeze beyond propylene glycol not being poisonous?
Bill Toensing, Nevada City, CA