The soluble oil I used is put out by McKay, cost $6 for a quart. The recommendation is for 2 ounces of oil to each gallon of radiator water.
Of course, the lowest temperature this car has been exposed to is in the mid 40s F.
"Ole"
-Distilled water is one of the worst things you could put in your radiator. Its absolute lack of ions accelerates the corrosion process. Try rainwater, or let some tapwater air out for a few days.
Jarrid Gross
I just got around to reading the Wed. post, so this is a bit late. I take strong exception to both of the above quoted comments. I do not have a Ph.D. behind my name, but have worked for some 30 years as a water treatment chemist and am currently the tech. dir. or a regional water treatment firm and am a long time member of NACE (national association of corrosion engineers). Our product line includes corrosion inhibitors for cooling systems for big marine diesel engines. We are not into the commercial antifreeze market.
The rational for using distilled water as the first part of the coolant is that it contains no minerals which will cause scale on the heat transfer surfaces. As Jarrid says it contains no minerals, so would if left alone be quite corrosive. This is why we add corrosion inhibitors. The idea behind a corrosion inhibitor is to lay down a barrier on the metal surface that is passive to the coolant. The ideal barrier film will be a few molecules thick and will have heat transfer charistics similar to the metal itself. This is where Ole's soluble oil gets off the boat. This technology form the '30's puts down a hydrophobic film at the heat transfer surfaces that is not only thick ( in molecular dimensions), but is also a poor heat transfer medium. It tends to trap any "gunk" that might be floating around and make the film thicker and a better insulator.
A good inhibitor should have:
1. Borax. The best pH for iron inhibition is over 10.0 but this high pH is hard on aluminum. Borax functions as a buffer to keep the pH in the 8.5 to 9.0 range which is a good compromise.
2. Nitrite. A iron inhibitor and not bad for copper and aluminum.
3. Silicate. Specific inhibitor for aluminum
4. Azole. Tolytriazole is the most common of this group and is specific for copper.
There are a bunch of other exotic things that have only recently appeared which may be used in conjunction with the above. The best advice I have seen here is to use a brand of antifreeze which states on the label "for use in aluminum engines". Then remember that glycol as it ages oxidizes to glycol acid, so your coolant should be damn well buffered, or be changed annually.
Paul Gilbert in New Orleans