Antifreeze question for Duke!

[Scooter L.]

[Duke W.]

Detailed antifreeze discussion

In the last couple of years I have moved away from my previous Dexcool recommendation for vintage Corvettes. There is some question as to whether Dexcool provides adequate protection for solder joints, and even if you have a SB with an aluminum radiator it has a soldered brass heater core. The subject is controversial. Some industry experts think Dexcool provides adequate solder protection, some don't. In any event, there is enough suspicion to warrant a change since a new type of antifreeze has become widely available in the last few years.

I now recommend Zerex G-05 for ALL vintage cars that have brass radiators or heater cores. I still recommend Dexcool for all GM cars that had Dexcool as OE, and it's okay for vintage SBs with aluminum radiators and C-48 since they have no solder anywhere in the system. If you have Dexcool in your vintage Corvette now, you don't have an emergency situation. Simply change to Zerex G-05 when the two year change window arrives.

Zerex G-05 has a specific HOAT (hybrid organic acid technology) anti-corrosion formulation package that has been factory fill for Mercedes Benz cars since the early eighties. It is now OE in all DC and Ford products, but Zerex G-05 is the first aftermarket blend that meets the spec. Prior to that it was only available at Mercedes dealers as "Mercedes Benz antifreeze" and Ford and DC probably also sell it under a house brand since they adopted it as OE beginning in 2001.

The industry consensus is now that a HOAT blend is best for vintage cars that originally had green or any car that still has soldered cooling system components.

Mix with distilled water to achieve a 50-55 percent antifreeze blend and FORGET the damned Water Wetter!

I have NO IDEA if the chemicals in Water Wetter are compatible with G-05 or any other antifreeze corrosion inhibitor package. Does anyone else?

If you use a modern antifreeze product, no additional additive products are required - just like using a modern HD diesel engine motor oil - no additional additives are necessary or desirable. Leave the additives on the shelf.

Water Wetter is probably a good idea if you have a race can and run straight water with no antifreeze, but that's the only application IMO. There is a myth that Water Wetter will "solve" overheating problems. If your car runs hot or overheats, find the root cause of the problem - ignition map, fan, stuck thermostat, clogged radiator, or a corroded water pump impeller, but it's totally worthless if you use a modern antifreeze product, and may even be harmful if there is any incompatibility with the antifreeze corrosion inhibitor package.

I also recommend a thorough system flush (just water, no chemicals) went switching antifreeze formulations.

If anyone wants to investigate this further go to the Valvoline Web site and look at all the antifreeze specs. There are now at least five different formulations. All are ethylene glycol based, but have different corrosion inhibitor formulations.

In addition to G-05 they offer a formulation that I think is unique to VW/Audi, but I can't remember if it's OAT or HOAT. They also have at least two OAT formulations, one of which is Dexcool, but the other is specific to the Japanese OEMs. There's one component in Dexcool they don't like, so they have their own OAT blend spec. They might also offer a traditional "green" IAT blend, but most manufacturers are phasing these out since NO OEM recommends them any longer for their current models.

The following is also a good article that you should print for future reference:

http://www.motor.com/magazine/pdf/082004_04.pdf

Life keeps getting more complicated!

Duke

[Scooter L.]

Re: Detailed antifreeze discussion

Thanks Duke,
One last question. Would you flush with tap water, and then use distilled water in the 50/50 mix? Or just use tap water all around? The water here in Oregon is pretty good, but better safe than sorry.
Scott #32911

[Gary S.]

Re: Detailed antifreeze discussion

It is always a good idea to flush the engine with tap water to rid it of as much of any old solution as possible. Don't forget the two block drains down in the area of the engine mounts. That will allow you to get rid of virtually all of the old mixture. These drains, 9/16" heads if I recall correctly, are often very stuck but a good soaking with PB Blaster or Kroil should loosen them. I have heard that some folks remove the block drains and nothing comes out due to solids settling out of solution and blocking them. I suspect that a little bit may settle there but will come out with a poke from a screw driver.

I did my engine and flushed until the water ran clear. I lightly reinstalled the block drains and radiator drain and filled it up again. Pulled the drains and flushed again. I repeated that several times and then filled with the proper mix. You WILL get wet and dirty, but, hey your having fun with your car!

Gary

[Duke W.]

Re: Detailed antifreeze discussion

Yes, flush with tap water. Many OEMs say clean, potable water is okay to use, but for about a buck a gallon, I use distilled water to mix with the antifreeze.

Duke