Date: Fri, 6 Oct 95 08:29:31 CDT From: "Dan Houg" Motor (automotive trade journal) Oct. 1982 The Great Debate -- by Paul Weissler When your customers come in for a cooling system flush and a fill of fresh antifreeze this fall, will you have the coolant recommended by the car manufacturers for their automobiles? Or for that matter, should you? Because of the increasing use of aluminum in engine components, there has been a lot of reformulation of antifreezes. And there's also a whopping disagreement among domestic and some European car manufacturers on what should be used. Here's the story behind the disagreement and some answers to questions on which antifreezes to use, how much to install, and how often to flush and fill. The questions all started with the Rabbit and the Scirocco, VW's entries in the water-cooled engine lineup. Five years ago, VW put out a well-publicized ban on antifreezes containing phosphate. The bas was reportedly based on laboratory tests of different antifreezes, in which it was found that phosphate, a popular corrosion inhibitor, would drop out of the antifreeze-water solution in very hard water. VW owners heard, quite correctly, that virtually all American antifreezes, including Prestone II, contain phosphate. So many owners ended up at the VW dealer, paying up to $11 a gallon for Autobahn brand antifreeze. But, surprise: In 1978, Chrysler introduced the Omni and Horizon with the VW engine and recommended Prestone II. The antifreeze producer claimed it was effective in preventing corrosion in the aluminum head. This is important because aluminum particles can deposit in the radiator tubes, causing plugging. Chrysler based its choice on its own tests of the different antifreezes. By contrast, the Autobahn antifreeze, though not as effective in preventing aluminum corrosion, holds the corrosion particles in solution so they don't cause radiator plugging. Union Carbide, maker of Prestone II, added its own explanation: Yes, some phosphate drops out of solution in very hard water, but the problem is not a real-world one. Further, phosphate in combination with other inhibitors is the best formula to prevent cavitation erosion of aluminum water pumps. Cavitation erosion is caused by the forceful collapse of coolant bubbles against the inside of the pump. The force is great enough to cause chipping off of aluminum particles. GM has used aluminum water pumps for years, and its performance standards for after-market antifreezes have always taken cavitation erosion into account. When Ford introduced its Escort in 1980, it published test procedures and standards to cover both the aluminum head and aluminum water pump for the engine. The water pump erosion tests included one for 1000 hours, a real toughie. In addition to the Ford procedures and standards, the antifreeze makers knew GM would have an aluminum head diesel V6 for 1982-- and very similar after-market antifreeze performance standards. That pretty well dictated the decision for the American antifreeze companies. They could meet Ford and forthcoming GM standards only with an antifreeze that contained phosphate and silicates. Silicate is an established inhibitor of aluminum corrosion, but it tends to jell as an ingredient in antifreeze. Silicone compounds are commonly used to prevent the jelling. Union Carbide has used silicone-silicate in Prestone for years, and current formulations by the other leading makers-- Dow, Northern Petrochemical (Peak), BASF Wyandotte, and Texaco (private branders)-- also contain silicates. At present, all have aluminum protection formulas that meet GM replacement and Ford O.E. specifications. In some instances, meeting the specifications is done by tweaking a basic formula to pass some unusually difficult pert of a factory test. However, even if the after-market formula doesn't pass every part of every test to the exact number, it comes close enough to ensure that there are no real-world troubles with normal maintenance. Chrysler has done limited testing but has to date approved a Prestone formula similar to Prestone II and a BASF formula. AMC's Renault Alliance has some special requirements that pose problems for other than Prestone II and BASF formulas, but that car probably won't need its first flush and fill for a year or more. By the time the Alliance needs one, the industry will have tweaked the formulas many times more. GM uses some of the antifreezes that meets its replacement specifications as factory fill on its aluminum-head diesel V6, a break with tradition. GM usually publishes a composition formula for an antifreeze and then takes bids from suppliers. However, it will not have the composition formula for aluminum-head engines ready until next spring, because of delays in completing test work. However, even when the GM composition formula is announced, the after-market antifreezes will continue to have GM approval as long as they continue to meet the performance specifications. There's an added touch of complexity in 1983, as Chrysler phases out the VW engine and begins to use a Peugeot 1.6L, aluminum-head engine. Peugeot doesn't prohibit phosphate, but it doesn't allow borate, which is used in all leading American (and VW) antifreezes. Peugeot has not announced its reasons, but they reportedly are based on laboratory tests with no more real-world meaning than the VW tests have. According to one American antifreeze manufacturer, Peugeot uses a benzoate-nitrite formul "that we consider inferior to all leading American brands." Peugeot doesn't sell many cars here, but you may have heard Peugeot owners say they were warned by the dealer not to use anything but Peugeot's own antifreeze, at a vintage wine price of $7 a liter. Chrysler has reportedly told Peugeot it was satisfied with the test results on American antifreeze in the Peugeot engine it was buying. Chrysler will use American antifreeze as factory fill and approve comparable antifreezes for replacement, not the Peugeot formula. So what happens if you use a leading American antifreeze formulated to prevent aluminum corrosion in a VW or Peugeot car with different factory antifreeze specifications? The answer is that the cooling system will get the same good protection that domestic engines and domestic cars with the imported engines get. By the time the first antifreeze change is due, the VW and Peugeot cars are out of warranty, so even this cannot be used to defend the installation of factory brands. ========================================================================= Date: Fri, 6 Oct 95 08:58:41 CDT From: "Dan Houg" Motor magazine Oct. 1982 Solder Bloom -- by Paul Weissler The quick move by American antifreeze makers to formulations that provide good protection against aluminum corrosion has, to date, apparently forestalled a problem. Even the VW antifreeze has apparently been successful in this regard. There do not seem to be a lot of radiators being plugged by aluminum particles transferred from the cylinder head. However, another cause of plugging persists; high-lead solder corrosion, called solder bloom, in the conventional copper-brass radiator. This corrosion shows up as a white deposit that can "bloom" over the tops of the radiator tubes, blocking them. It's a problem that has nothing to do with the engine but results from the type of solder used at the tube-to-header joints, and in some cases, the way the solder is applied. There's no antifreeze inhibitor formula that seems to be able to stop it cold for long periods. The problem of solder bloom is also unpredictable. Some radiators in some models years are apparently more prone than others. In any case, the problem usually takes several years to develop, and you can see it through the radiator fill neck. Once you find it, about the only cure is to have the radiator cleaned. The best results are obtained with an ultrasonic cleaner, although a radiator shop's boilout tank may work if the cleaning solution is up to proper temperature and the caustic concentration is adequate. Never use the two-step oxalic acid cleaning method to remove solder bloom. Although some pour-in radiator cleaners are recommended for solder-bloom, the results are inconsistent and are poor if the bloom is severe. The crimped-together and epoxy-sealed aluminum radiators do not encounter the solder bloom problem. However, their durability is yet to be proved. The early Rabbit and Scirocco radiators, for example, may be failing at a rate higher than conventional radiators, according to the National Automotive Radiator Service Association. There failures are primarily perforation-- that is, corrosion of the aluminum tubes starting from the inside and coming through. There is some indication that VW aluminum radiators aren't tolerant of cooling system neglect. VW's failure to prescribe cooling system flush and fill intervals may be a factor. ========================================================================= Date: Fri, 6 Oct 95 09:19:02 CDT From: "Dan Houg" The following is a summary from Prestone Corp.: -PG IS LESS TOXIC TO MAMMALS -BOTH RELATIVELY NON-TOXIC TO AQUATIC LIFE -BOTH READILY DEGRADE TO CO2 AND H2O -PG IS LESS EFFECTIVE AT LOWERING FREEZING POINT AND RAISING THE BOILING POINT OF WATER -PG IS MORE VISCOUS AT LOW TEMPERATURES -PG CONCENTRATIONS CANNOT BE DETERMINED WITH HYDROMETER -PG COOLANT IS A POORER CONVECTIVE HEAT TRANSFER FLUID THAN IS EG COOLANT AT SAME CONCENTRATION -PG COOLEANT PROVIDES COOLER METAL TEMPERATURES AT CYLINDER HEAD HOT SPOTS UNDER BOILING CONDITIONS THAN DOES EG COOLANT AT SAME CONCENTRATION ======================================================================== 99 Date: Fri, 6 Oct 95 09:36:33 CDT From: "Dan Houg" The following info from Prestone Corp.: TYPICAL NORTH AMERICAN COOLANTS -phosphate and/or borate -high silicate -nitrate -triazole -antifoam -pH 10.0-10.5 TYPICAL EUROPEAN COOLANT -benzoate -borate -silicate -nitrate -triazole -antifoam -pH 8.0-8.5 PRESTONE Antifreeze -phosphate -borate -silicate (high) -nitrate -tolyltriazole PRESTONE LONG LIFE 4/60 -organic acids -silicate (low) -tolytriazole -nitrate -molybdate Here is the formula of a typical antifreeze coolant concentrate that is safe for aluminum components: Wt. % ethylene glycol 95.56 sodium nitrate .10 sodium molybdate .20 sodium tetraborate .40 sodium silicate solution .30 phosphoric acid .15 MBT (50% solution) .50 TT (50% solution) .20 sodium hydroxide .235 water 2.30 polyalcohol .05 dye .005 MBT (mercaptobenzothiazole) is a corrosion inhibitor for copper or brass. TT (tolytriazole) provides protection similar to MBT, but TT is more durable at higher temperatures. Nitrates are corrosion inhibitors for ferrous surfaces, and protect from pitting and crevice corrosion. Silicates inhibit corrosion on hot aluminum surfaces, and provide protection from cavitation. Silicates also act as general purpose chemical buffering agents. Borates provide buffering and neutralizion of acidic and sulfurous combustion gas by-products. Sodium hydroxide helps stabilize pH. Silicones are antifoam agaents which also slow the silicate reaction with magnesium. Polyalcohol supresses the formation of foam. Phosphates provide general purpose protection for several metals and are effective in preventing the cavitation-erosion damage of aluminum. ======================================================================== (1983.5 - 1991 Models Vanagons only) COOLANT/ANTI-FREEZE: Recommended coolant/anti-freeze: Autobahn ZVW-237-104 antifreeze & summer coolant Phosphate free formula for use in Volkswagen & Audi water cooled vehicles Ethylene Glycol based, Phosphate free recommended mixture: not less than 40 percent coolant, not more than 60 percent. sold at VW dealers only. manufactured by BASF Questions? Call 1-800-669-2273 BASF Customer Service: 1-800-445-4134 BASF Marketing Service: 1-800-367-9865 BASF Technical Service: 1-800-521-9100 Info from Marketing Service: BASF makes a 'generic' brand of GUARANTEED Phosphate Free coolant called ZEREX EXTREME 450. It has been approved by VW, BMW, MB, Audi, Saab, and Volvo. It is also GUARANTEED for four (4) years and 50,000 miles. They said you CANNOT mix this with any other coolant; you must flush the system and fill with the new coolant/water mix. Info from Tech Svc: BASF makes two (2) european formula coolants. One is sold by VW, Audi, and Mercedes Dealers. The other is sold by BMW, Saab, and Volvo dealers. The reason for the phosphate free formula is basically two-fold: (1) Cosmetics: Hard water reacts with phosphates in coolant to form scale deposits in overflow bottles. These deposits could form in other parts of the cooling system, causing blockage and overheating (see next part). (2) Corrosion: Phosphates tend to aggravate any corrosion that might already be present with any aluminum parts in the cooling system. Aluminum Phosphate is formed, which is insoluble in the ethylene glycol solution of the coolant. The aluminum phosphate will tend to settle out in the cooler areas of the cooling system, causing blockage. This can cause overheating of the engine, which will accelerate the aluminum corrosion. In other words, the corrosion will tend to feed on itself until damage is done to the engine or the coolant is replaced (refreshing the inhibitors). Engine coolant should be REPLACED every two (2) years to refresh the silicates and other corrosion inhibitors contained in the coolant. He was not aware of any problems with coolants containing phosphates, but did say that if the coolant was NOT replaced regularly, the inhibitors would lose their effectiveness and become weak. And that weakness could allow some aluminum corrosion to start, and become aggravated over time. ======================================================================== this is a letter written to Road & Track magazine, Technical Correspondence column, for the July 1996 issue: White Stuff ----------- I used to think the white stuff that plugs up radiator tubes came from impure water, but after using only distilled water and ethylene glycol and still getting plugged tubes, I called a radiator shop. A spokesman called it "lead bloom." He didn't seem to know where it came from, though. My older cars and tractors don't seem to have this problem. Could it be from the alumninum used in newer motors? I can't find anybody who knows. And what can be done to minimize its formation? --------------------- Mike McGuire at Unigard was also unfamiliar with the term "lead bloom" but gave several clues as to the source of your "white stuff." Running straight water or old, worn-out antifreeze or antifreeze diluted by topping off with straight water corrodes aluminum and yields a pasty white goop. Mike pointed out that the agents in antifreeze that protect against aluminum corrosion -- silicates -- wear out, and replacing the antifreeze every 30,000 miles or two years is the only cure. So, while you may have freezing protection if your coolant is old, it won't protect against aluminum corrosion. Another source of white contaminants is silica dropout. This occurs in all-iron engines running high-silicate antifreeze, where there is no aluminum for the silicates to chemically work with. If you have an iron engine, inspect the antifreeze label for a phrase about compatibility with heavy-duty engines. It is a good sign that antifreeze is a low-silicate blend. This is because the long-haul engines from Cummins, Detroit Diesel and others are always all-iron, and require a low-silicat antifreeze. Just for the record, distilled water can cause its own problems because it has such a low pH. Water will seek its own balanced pH, and when distilled water is placed next to aluminum, it leaches the minerals it wants from the alloy and black soot forms in the coolant. That's why silicates are put in aluminum-compatible antifreeze; they're sacrificial mineral deposits.