Zerex G-05

[Rex T.]

Re: Zerex G-05

Oops - my bad - I meant to say G-05, not Z-05. The least expensive way is to buy the full strength type and mix it approx. 50-50 with distilled water.

Change it every five years - completely drain the system by opening the radiator drain cock and pulling the block drain plugs. Look at the owner's manual for your engine-heater configuration, add about half the stated capacity G-05, and top off with distilled water.

The capacity is for a completely empty system, and even pulling the drain plugs will leave some residual, so you will end up with about a 55 percent concentration of the G-05, and the target range is 50-60 percent.

Duke

Duke,

In 2008 I installed my new ZL-1 427 engine and new DeWitts aluminum radiator in my 67 Corvette. I filled the cooling system with a 50/50 mix of Zerex G-05 and distilled water. Since 2008 I have put less than 300 miles on the car. In your opinion, should I drain the cooling system and replenish with a new fresh mix of G-05 and distilled water?

Thanks in advance for the help and suggestions.

Rex

[Duke W.]

Re: Zerex G-05

Tough call, Rex. The bulk coolant is probably okay, but the problem with lack of operation is localized depletion of the corrosion inhibitors due to lack of coolant circulation, which can lead to localized corrosion. You should drive it at least once every month to two for at least 20-30 minutes in mild to hot weather to get it fully warmed up and circulate the coolant.

As you know, aluminum is a lot less forgiving than cast iron. I demonstrate this when guys drop in by showing them a Cosworth Vega water pump casting I have (but not from my CV) that has several corrosion holes all the way through the inlet nipple and lots of corrosion craters where the inlet hose was attached.

Also, the CV block has an open deck architecture, and a favorite place for localized corrosion is the top of the cylinder barrels. The ones I've see look like someone took a die grinder and beveled the tops of the barrels from the outside in. The end result is a blown head gasket and the block must be sleeved with cast iron liners.

About 15 years ago at our National Roundup in Las Vegas a guy showed up with an orange CV that had just a few thousand miles - beautiful car, but I was suspicious. Sure enough, a few months later I heard that the head gasket blew out. My bet is that is still had the original Lordstown coolant fill, which at that point was about 25 years old!

Not long after I had to pull my CV's head for a refresh, and the cooling jacket and barrels looked brand new. Back in the day I changed the "green" anti-freeze every two years. Now I use G-05 and change it every five.

Duke

[Rex T.]

Re: Zerex G-05

Thanks Duke. I'll be changing mine soon.

Rex

[Mark E.]

Re: Zerex G-05

I may have selected the wrong coolant for my '70 LS5.

After re-coring the radiator and flushing the system, I filled 50/50 with Zerex Original Green and distilled water. I believe this is the old-school ethylene glycol-based stuff that also meets GM 1899M and 1825M.

I since learned from this Forum that Zerex G-05 may be a better choice. My understanding is G-05 also ethylene glycol-based, meets GM 1899M and 1825M, but also uses HOAT.

So is G-05 really less likely "to clog up radiator tubes" than Original Green, as suggested in this and other threads?

If yes, since both of these products are ethylene glycol-based, can I just drain the system as much as I can using the petcock (vs. completely flushing out the Original Green), then add G-05 to the remaining Original Green in the system to gain its benefits? I realize this may be a question for Valvoline/Zerex, but thought I'd ask.

[Larry M.]

Re: Zerex G-05

Mark:

The answers to you questions are:

1. Yes

2. Yes. Obviously the best way to changeover is to drain both the radiator and the block. No flushing needed. Another way to accomplish about the same is to drain the radiator and refill the system with distilled water. Run the car until hot and then drain. Repeat again. After this refill with G-05.

You can also just drain the radiator and refill with G-05. It is compatible and won't hurt anything, but you will not get the full benefit from the G-05. However, continued use of G-05 over the years should eventually remove any residual from the earlier "green" type.

Larry

[Mark E.]

Re: Zerex G-05

Thanks Larry.

The block's drain plugs seem hopelessly frozen in place, hence my question about mixing the two coolants. I like your idea about draining/filling with water a few times.

[Joe L.]

Re: Zerex G-05

Thanks Larry.

The block's drain plugs seem hopelessly frozen in place, hence my question about mixing the two coolants. I like your idea about draining/filling with water a few times.

Mark------

While I think that Zerex G-05 is best for 1953-96 Corvettes, it's primarily based on anti-corrosion for copper/brass components. However, it's certainly not vastly superior to the "yellow-green" stuff in this regard. It's really only slightly superior. As far as "tube clogging" goes, I used the "yellow-green" stuff for years and never had any problem like this.

If I were you, I'd leave the "yellow-green" stuff in your system. The real benefit you would achieve by switching to the G-05 is so slight it's just not worth it.