Exactly!! I just love the knee jerk reactions some people have before they know all the facts.

To answer the rust question, water and WW must have a rust inhibitor added. They are available at the normal parts stores, Advance, etc.

Keep reading. It was in there, I haven't read it in a while. But last time I did, it was there in print. If it's not, it may have been accidently left out. Some times that happened on the new revisions.

The only reason to use anti-freeze is for sub 20deg. temp and for water pump lube/rust inhibitor. Water cools better.
I know the OP question has been answered. But as it often does, The thread took a turn went someone basically said. Just run anti-freeze anyways. Even after every other person brought up the dangers of doing so, he continues to say "screw you guy, I'll do what I want". It's not a knee jerk reaction, it is a deep concern that we all do the right thing.

It's a point of "Safety for all"! Just because you carry a loaded pistol with a hair trigger pointing it at people for years with out a problem. Dose not make it right nor safe.

Gian, you make some good points, however, to race successfully, you must know the rule book completely and be prepared to take advantage any way you can. Your altruism is notable but as I have said, I have provided an alternative...it is up to the individual to follow through or not. If you are not comfortable doing so, by all means don't. But don't condemn me for following the rule book!

Well Chuck, I understand the rules guide us all. I know them well being a National contender in both SCCA and NASA. Inside an out in fact. I've had a few changed in SCCA because they were wrong. But just like you have a bad taste in NASA, I have for SCCA. So I will leave you to do what ever you thing is right. Not like I going to change your mind anyway.

But for the rest that do use water in your cooling system. It's best to change your water/coolent every year. Distilled water can corrode, but hard water leaves calcium. Water wetter is basicly soap. Water pump lube will also leave deposits and gum up. Even coolant has it's problems. All cooling systems build electrolysis from the motion of the water passing through the system.
This electrolysis is what kills our cooling systems. The only way to get rid of it, is to drain it.

So it's best to drain the cooling system once a year. Some go as far as draining and putting pure coolant in the off season. Pickling it as it were.

Rocklobster...I'll be at Brainerd on labor day...come and visit!!

NASA actually now allows the racing version of evans coolant. You're welcome...

I've also never had corrosion issues with a full bottle of purple ice and straight soft water. But some guys want to run evans which in a rotary is a really good idea for a few reasons, hence the racing stuff they make.

Brained is a heck of a long haul from the south....what inspired such a trip?

Friend bought my ITA BMW and then had me build him a BMW Chump car. Also bought an ITS BMW. He came here to pick up the Chump and ITS cars and we went to Savannah to test/race. So I'm going up there for the labor day race. I get to drive 19 hours instead of 19 minutes!! Bucket list checked off.

Brainerd is a cool track, mix of technical new section and old school road course layout. You'll have fun.

Was there last Labor Day delivering my ITA car. Did drive track for a couple of laps. Very reminiscent of Roebling Road...mostly flat, some fast, some slow corners. Looking forward to the weekend.

If coolant isn't mentioned in the SCCA GCR or NASA rules you should also check the specific event supplementals. I'll bet you will find them there. The track owners know what chaos it will cause.