How often to change antifreeze

[Gary G.]

Gentlemen,
I use the old green antifreeze in my 75 coupe. I drive about 1500 miles per year with the car. I have changed the coolant every two years since I have owned the car. Can I extend the interval, or should I continue the current practice?

[Terry M.]

Re: How often to change antifreeze

I would stick with every two years -- it might be overkill, but anti-freeze is inexpensive.

I gave up on the green years ago.

[Duke W.]

Re: How often to change antifreeze

Start using Zerex G05 and you can extend the drain intervals for an occasionally driven car. There's lots of information on Zerex G05 in the archives.

"Green" is obsolete - no OEMs use it, it builds up deposits over time, and the best current technology replacement is a HOAT formulation like G05, which is OE from Ford, Chrysler, and Mercedes, and their recommended drain intervals are at least three years.

Duke

[Tom R.]

Re: How often to change antifreeze

Start using Zerex G05 and you can extend the drain intervals for an occasionally driven car. There's lots of information on Zerex G05 in the archives. Duke

The chart at Zerex does not recommend the G05 for GM vehicles pre 96 or am I missing something? Of course...this topic is above my pay grade but if experience shows G05...I'm there. And of course the assumption is C3 era motors.

http://www.valvoline.com/zerex/automaker.asp

[Edward J.]

Re: How often to change antifreeze

Gary,
Ive Been Working On Cars For A Living For 35 Years , A Quick Note, Go5 Is Made For Car With Bi- Metal Engines, Today Engines Contain Alum. Cat Iron, And Some Plastic Componets With Anti Freeze Running Through Them ,not To Say That This Formula Wont Work In You Car Because It Will. But I Put Green In My Car Every Two Years ( Prestone,been Around For Ever, Great Stuff)

[Duke W.]

Re: How often to change antifreeze

My rationale/reasons for recommending G-05 and discussions of the various corrosion inhibitor technologies are in the archives. The subject has been dissected/discussed almost as much as engine oil.

Duke

[Edward J.]

Re: How often to change antifreeze

Duke,
There Are Quite A Few Exteneded Life Anti Freezes Out There To Replace The Green Type , Go5 Is Good Stuff , But Better For Later Model Cars,besides We Need A Reason To Tell The Wife Ive Got To Go To The Garage To Change The Anti Freeze. Gary, You Can Change To Longer Life Anti Freeze Just Look On The Shelfs, Most Anti Freezes Are Long Life Today And Have Good Qualitys.

[Lorne G.]

Re: How often to change antifreeze

I just finished restoring my 67 and went to my local NAPA for Antifreeze. They actually recommended that I use the green antifreeze for pre-eighties cars.
They had lots in stock ( at least in Canada)
Lorne

[Gary G.]

Re: How often to change antifreeze

Gentlemen,
I can see the benefits of each type of fluid. I purchased some NAPA antifreeze today, and plan to do a flush in the spring with the "old green." Next time, I'll get ambitious and change over to the GO5.
Thanks for all of the input.

[Duke W.]

Re: How often to change antifreeze

They actually recommended that I use the green antifreeze for pre-eighties cars.
They had lots in stock ( at least in Canada)
Lorne

Oh, okay. The next time I need antifreeze, I'll ignore all my research (and past experience with silicate clogged radiator tubes on cars I've owned for several decades) and ask the NAPA counter guy what to use.

I may even help him out by saying I'll take whatever you have too much stock of and pay full price.

Gee, I'm such a great guy!

Duke

[Michael A.]

Re: How often to change antifreeze

I'm with Duke. Duke's recommmendations are solid, well researched and well explained in the archives. I'm thrilled with the tire recommendations (Pirelli P4000 Super Touring) and filled the cooling system with Zerex last year.

Duke, you are at least several steps above even the best NAPA parts guy:-)

Cheers,

[John S.]

Re: How often to change antifreeze

Duke,

Are there any special draining/cleaning procedures that need to be perform when switching from green to G05? Are they on the container? I am going to be changing mine soon. Thanks

John

[Gary G.]

Re: How often to change antifreeze

The flushing procedure concerns me too. I am willing to switch to the Zerex, but the drain plugs have never been out of my block. I don't know if I can remove them in my garage. If most of the old type antifreeze is removed, will there be a compatablility problem with the GO5?
I have read the archives, and I am leaning to making the change in fluid type sooner than later, and I am not in any urgent need of a change right now. I am still trying to make the best decision. I thank everyone for the great information on this board.

[Duke W.]

Re: How often to change antifreeze

I always recommend removing the block drain plugs. Use a six point socket and shock them with a big breaker bar. If no fluid flows after the plugs are out dig out the deposits with a pick until the opening is clear.

Clean the threads, apply some pipe joint compound and tighten them to just "snug" - no more than about 8-10 lb-ft, maximum. There are no standard torque values for pipe threads like exist for SAE bolts. Basic guidance is to tighten them so they don't leak. With pipe joint compound this isn't much and the compound will keep them from vibrating loose. Pipe threads typically seize because the plugs were installed with no compound and tightened too much.

If you cannot remove the block plugs drain the radiator and fill with water. Run until the thermostat opens. Repeat this process until the drain water is clear and tasteless. It may take several cycles.

I recommend a thorough water flush when switching to G05 from green although it's more important if you switch to Dexcool, which I no longer recommend for vintage Corvettes.

You can also reverse flush the system from the heater hose nipple in the manifold. "Kits" are available at auto parts stores to adapt a garden hose to the heater hose nipple, and you can make your own with a bit of 5/8" heater or garden hose, a valve, and adapters than you can buy at hardware stores.

I don't recommend any chemical "radiator flush" products. They will not remove heavy deposits. Once the radiator deposit buildup is enough to cause hot running/overheating at highway speed, the radiator is likely toast, and the aluminum radiator needs to be replaced, but brass can be rebuilt.

The high silicate content of traditional "green" is what causes this deposit buildup. G05 will only build up deposits at a small fraction of the rate of green, so a new aluminum or properly rebuilt brass radiator should last longer than most of us with coolant changes every 3-4 years.

Duke

[Gary G.]

Re: How often to change antifreeze

Excellent information Mr. Williams. I will do this as soon as I get warmer weather here. Thank you all very much.