I wonder why its banned on trackdays?
This has been long discussed. Engine Ice was at one time a race sponsor in the US. Engine Ice was permitted in that series. There was a serious incident after a coolant spill. Glycol coolants are no longer allowed.
[video=youtube;4VcM01L0iSQ]https://www.youtube.com/watch?v=4VcM01L0iSQ[/video]
Engine Ice is a propylene glycol based coolant, it has all the same properties when it comes to spills and clean-up as far as tracks are concerned. So, it's banned.
However, propylene glycol coolant is an excellent choice for the street. It has all the freeze and boil protection of ethylene glycol and it less hazardous to the environment. Propylene glycol is in fact a food grade product and is used in pharmaceuticals, cosmetics and some foods.
Most of the hype about Engine Ice been removed from their website. It was all marketing BS, none of which could be proven true. Propylene glycol has a slightly higher viscosity, slightly lower heat absorption rate, and slightly lower heat capacity by volume than ethylene glycol. This adds up to about a 5% penalty using propylene glycol. Not usually a problem in street use. Modifications can be made to systems to improve the Reynolds number (turbulent flow) and thereby improve coolant performance, but again, not usually needed in street use.
You will NOT see a 20 degree temperature reduction. Your thermostat controls coolant temperature. You may see a slightly elevated temperature on hot days, stopped in traffic. Nothing to worry about; elevating the coolant temperature improves heat transfer through the rad to the air.
I don't know why Engine Ice suggests replacing every year in street use, or twice a year in racing (not allowed anyway). There is little difference between Engine Ice and any of the other propylene glycol based coolants, many of which are "long life".
ended up getting a second jug of engine ice, but for some reason one looks blue and one looks purple?!
My guess would be that Engine Ice uses a "co-packer" to package their product and there are slight variations from one supplier to another. Probably not a concern.