If you drive a diesel as many of us do you probably have SCA in your cooling system.
SCA by whatever name it's known keeps the micro-boiling cavitation/vacuum bubbles from etching away at the outer side of your cylinder sleeves. The SCA forms a super hard coating wherever the bubbles form. Too much SCA and the coating breaks off and it turns into a very fine abrasive sludge which will eat the vanes off your water pump and other moving parts. This is the #1 reason for waterpump failures in diesels, #2 being sand left in the casting.
I highly recommend a coolant bypass filter for all diesels.
All of this from
www.thedieselstop.com