A proper mixture of coolant is a 50/50 mix of clean low mineral water with ethelyne glycol (permanent type anti-freeze). It should also contain corrosion inhibiters and water pump lubricant. Dupont or any name brand should be adequate. Be sure it says compatible with aluminum, most all of the top brands do. If you have this concentration in the system and you can hold 15 psi the boiling point is 256 degrees F. The problem is if you lose pressure containment at a temperature above 212 degrees you will get an immediate flash boil over. This is why it is so important to have a good tight system with hoses you can trust, If ANY hose anywhere in the system fails including the heater hoses, radiator cap etc you will immediatly lose all coolant and all cooling capacity in the system. There will be no "buffer" or margin of safety in the event of a loss of pressure containment. You will immediatly overheat. The first sign may not even be a rise on the temp gauge, it won't respond fast enough. Typically most drivers will first notice that the engine doesn'trespond to the gas pedal. There may be some unfamiliar odors and then it may occur to look at the temp gauge. By then it is way past too late and all you can do is shut the engine down and coast to the side of the road. David Teitelbaum vin 10757 --- In dmcnews@xxxxxxxxxxx, "Robert Rooney" <dmcvegas@xxxx> wrote: > My cooling fans don't turn on untill a little bit below the 220 mark. > While the motor appears to run fine @ this temp, I don't know that > it's the ideal range. I've found that when the temp gets up that > high, the heat robs the engine of power. For good pickup and power, > the car performs best in the 160-190 range. Plus for the coolant > mixture that I use, 220 is only 15-20 degrees below the boiling > point. When a cooling system failure occurs there is not a safe > enough "buffer zone" to give me enough time to pull the car over to > the side of the road before the radiator cap blows. (ie: if while in > heavy traffic the cooling fans didn't turn on because of a blown > fuse, I could pull over to cool the engine down while I replaced the > fuse. And then continue down the road. But if the coolant boils over > before I can pull over, I'm then stranded no matter what because I've > dumped the majority of my water out.) > As for the the otterstat, the unit is sealed so you can't adjust it > to have the fans kick on @ different temps. > > -Robert > vin 6585 > > --- In dmcnews@xxxxxxxxxxx, joelpash@xxxx wrote: > > Is 220 when the needle is right in the middle? If I remember > > correctly, this is where it is supposed to run. The engine is > > designed to run hot. It is possible to set the fans to come on at a > > lower temp, but then the fans will not last as long.