Blue vs Green Coolant- Fight!

By Dennis Haynes

To begin I wish to apologize for not keeping up with the list and this discussion. I have been a bit busy and this topic seems to get attention like oil and tires. There is just a lot of information out there and probably the best feature of many products is the advertising.

For my experience I have dealt with cooling systems and water treatment for vehicles and numerous industrial systems. The good, bad, and sometimes ugly. I have been amazed how truly de-ionized water can discolor (rouging) stainless steels.

I have been working on VWs since about 1974 and grew up with the introduction of the VW water cooled stuff and even owned some Sciroccos and an 81 Rabbit convertible before getting into Vanagons. Back in the day due to advertising and perceptions most everything got Prestone Green Stuff. Except for an occasional water pump I never knew I had an antifreeze choice problem. Even my first Vanagon, an 84 GL passenger that I purchased about a year old got the green stuff after a water pump change. I sold it at 96K as I needed $$$ to help acquire Fun Bus. That was February 1988.

So let’s talk about Fun Bus! Yes I still have it and lately been using as a daily driver. I am hoping to get it to 350K. I have less than 38K to go. While I have had to do a number of transmission repairs, (Broke 4th gear twice 3-4 slider hub, and a pinion bearing), the engine has never been opened. Currently you can tell where it was parked by the Mobil 1 dripping from the crankshaft seals, (both now), but it still has proper compression, good oil pressure, and the antifreeze leaks now are mostly the heater cores. I did have to replace the valve covers a few years ago as they rusted out enough to leak. Also, once the Vanagon lifter clatter let the push rod fall out the rocker socket for intake valve cylinder 1. However the heads have never been off.

How often do I change antifreeze? Not very. It seems that during “condition based” maintenance there is always a reason to open the cooling system more often than modern antifreezes need to be replaced. Unlike lubrication frequent additions, top offs, and even excessive coolant changes is not a good thing. Why, when you add fresh coolant or water you are adding fresh oxygen. If you have leaks you are also losing fluid but leaving the bad stuff behind and overtime the bad stuff gets concentrated. So the most important part of cooling system maintenance is to not have leaks. In theory the only loss you should have is evaporation from the recovery tank.

The science! I am sure some folks here have home heating systems with radiators or baseboards. Cast iron boilers, copper pipes, valves with steel parts, etc. They all last for 20 to 30 years and there are no additives used all. Fill the system, let the oxygen purge out, metals or whatever reach equilibrium and the stuff is just there.

Now let’s look at the Waterboxer head gasket failure from corrosion problem. For all those that have worked on these and seen the corrosion on the head and also on the case where the gasket sits have you noticed that the corrosion is only in that area? Well, at that point it does not matter the choice or age of the coolant! The gasket (sealant) was failing long before the corrosion.  That’s right. If the gasket seal was good the antifreeze wouldn’t be there. However, once it is there the heated coolant mixture mixes with air and the corrosion process begins.

So now let’s talk about antifreeze types. Back in 1999 I purchased a new motor home. Ford chassis with the Triton V-10 engine. There were numerous stickers near the coolant tank warning to use only specified fluids and NOT to use Dex-Cool. This took me by surprise. After all Dex-Cool was the long life antifreeze darling at the time. My antifreeze education was about to begin.

Fast forward to 2004 and the motor home gets upgraded to one with a Cat Diesel. Diesels it turns out have a whole different bunch of requirements. So I got to learn about cylinder cavitation erosion and all the additives or special antifreezes that deal with that. Also the need for longer life requirements and less abrasives to extend water pump seal life and reduced internal wear of really expensive radiators and stuff.

OK so back to my experience. Of all the engines and cooling systems I’ve worked the coolants that seems to leave the nastiest stuff inside an engine include Dex Cool and the Blue stuff. The Blue stuff is an older technology and I just don’t see a real advantage of it.  Dex-Cool seems to only work in systems designed for it. Flow velocity has to be part of that system design. As I truly like to reduce maintenance requirements (lazy) I became intrigued with the long life solutions used in the large Diesels and industrial uses. The state of the art for these applications include coolants such as Global Final Charge. These are 6 year, 600,000 mile coolants that only require an additive update at the half life for the cylinder cavitation prevention. These coolants also have great “wetting” abilities which improve cooling performance. The only real downside is that with the lower surface tension if there is a chance for a leak there will be one. Using these in the vanagon seems to also have another benefit, extended water pump life. Since these coolants rely less on abrasives for corrosion control water pump seal life is greatly extended.

Fun Bus and most of my customers now run on this. I also do use the pre-mix. It is convenient and I end up with a more consistent mixture. Yes, there is more cost for the “water” part but I know the mixture is correct. Also for winter fill, I have seen the water and antifreeze fills not get mixed enough and cause freeze damage. Especially if a fill is done and you can’t get the engine running long enough to really get the coolant mixed.

As for adding a wetting additive such as “Water Wetter” these high performance Diesel antifreezes have that covered. Like good oils, use the good stuff and additives are not needed.