Sorry for the bad photo taking a picture through a refractometer is extremely difficult but it tells the "rest of the story". I actually used my iPhone to snap this shot but it was still impossible to get a crisp photo. This was the best of about 30 shots of the same reading....


Out of the bottle this product measures about 4F on the refractometer. The goal is to match the bottles refractometer measurement/reading with what is coming out the exhaust. Please understand that PG will ice up/slush up well before it ever bursts. Most -50F rated PG products will turn to slush at around 0F to 10F. For proper burst protection it is critically important to NOT dilute it because the burst point raises rather dramatically when diluted more than what the bottle already is.


In this sample, taken at 8 gallons, the freeze/slush point is around 27F indicating a strongly diluted sample. It should read 4F just as it came out of the bottle.