Antifreeze/Coolant Service Intervals

100% distilled water is best for keeping the engine cool. But, that is not good for temperatures below 32F. I use a 75% water-25% coolant mix in my BB512i as which is great for Georgia summers and provides plenty of protection for relatively mild Georgia winters...

 

Kind of surprised that no one mentioned electrolysis, or other accelerated wear because of lower AF concentrations. I am far from an expert but I did some reading on this recently and this is what I found:

Most AF has ingredients added to reduce electrolysis. I also read a very interesting paper, complete with microscopic analysis of parts, that said the problem isn't electrolysis. The paper says that the problem is related to impurities in the AF and water precipitating out and creating a localized chemical reaction. The problem is aggravated by a PH shift in the AF that accumulates over time. Together they cause rapid chemical etching of aluminum. The degradation can be minimized by changing AF regularly (2 years or less) and using distilled water.

About water being the best coolant, kind of true but kind of not too. Water has a higher conductivity than a 50/50 mix so it can move more heat away from the surface. The bad news is that when placed on hot surfaces the water boils and creates air pockets at the boundary between the surface and the water. The air gaps (bubbles) has lower conductivity so you get less cooling. That means that the situation can rapidly change if the engine overheats.

There are additives that change the surface tension of the water keeping it from forming bubbles easily. These additives will significantly lower the running temp. AF does this too but to a lesser degree so it generally runs a little hotter than water alone. NOTE: water alone will have problems with electrolysis and accelerated wear.

 

Best water to use is distilled. Second best water is softened water. Distilled water doesn't contain ions such as calcium and magnesium to carry the current, complete the electrolysis cell and precipitate on the metal surface causing corrosion at that spot. I am old enough to remember back in the 70's when a radiator was chemically cleaned to remove the calcium and magnesium scale, the radiator often developed leaks. This is because the scale caused prevented the metal surface from getting the corrosion inhibitors in eh AF and so corrosion occurred under the scale. When the chemical cleaning was performed, the scale was removed leaving a pinhole and thus a leaking radiator.

Remember, three things are needed for corrosion to occur. They are a metal surface, oxygen and water. Remove any one of these and you will get no corrosion. (How many rusty cars are there in Arizona?) If you keep your cooling system closed, the dissolved oxygen in freshly changed antifreeze (AF) gets consumed on the metal surfaces and then no more oxygen is available to corrode the metal. So, frequent AF changes really aren't recommended and really aren't needed. Changing the AF every 3 years should be just fine. However that interval can change depending on how much and how hard you drive the car.

The pH shift is from the glycol breaking down over time to form organic acids. Thus, ther is a pH shift to an acidic pH. Additives include borate to buffer the pH up around 8-8.5 and this is enough to address any pH issues for the specific AF recommended life, which is typically 3-5 years.

If anything really should be changed or at least flushed it is the brake fluid because it will absorb moisture and can cause premature failure. Brake fluid turns dark brown and that is a good indicator it needs replacing.

 

I buy everything except this part. Water softeners add various salts to the water to give it that 'soft' feeling. Those salts contain the very elements that are bad.

 

GM uses dexcool. There have been several recalls on dexcool over the years because it was blamed on eaten radiators and heater cores. Just recently I did my biannual flush on my GM truck. After a very short time it sprung a leak in the heatercore!!!! A friend who owns a radiator supply company to the OEM's asked me what I put in the radiator. I said OEM Dexcool. He said Dexcool had a recall a while back and maybe I got some old stock. Rumour or truth? I have no clue but my truck is just a few years old and perfectly maintained and never needed anything but routine service. After my radiator service it springs a leak. Hmmm.... All I know is I have to take the entire car apart from the window glass to the rear seats to get the core out. You should see the mess I got going right now. I have parts all over the place. Anyway...I'm going back to the old school green stuff in everything and just change it often. For another datapoint I had perfect results over 10 years running my 348 on the race track with nothing but water wetter and water. I only put maybe 30% green stuff in when I knew it was going to get below freezing overnight before a race. Water wetter is supposed to have the anticorrosion stuff in there. If it does which my datapoint seems to prove then the only reason for E. Gylcol is for anti-freeze. Does anyone know about sacrificial anodes in radiators?

 

No not really, soft water is water that has had the calcium and magnesium removed and replaced with sodium. The calcium and magnesium are the source of scale deposits while sodium doesn't scale. Sodium remains in solution and the corrosion control additives function as they should. However, with the sodium comes the ability to have an electrolytic cell. You will get this anytime two different metals are in contact with each other. The ions in the water complete the electric pathway and you can get galvanic corrosion. This is why distilled water is best.

 

I've heard about it and bought an anode a couple of years ago but never installed it.

 

Mr. Roush was kind enough to include the attached basic article on the subject in the FML (has it really been 15 years ago!). I ran Mg anodes in my ex-308 for a few years prior to selling it, but it was really an attempt to minimize corrosion in the engine, rather than protecting the radiator (i.e., a brass radiator is at risk when used with an iron-based engine, but it's the aluminum-based engine that's at risk when used with a brass radiator).

What's your interest and/or application? I've got ~40 Mg anodes left in a drawer somewhere if you'd like some samples to experiment with.
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Just been looking through the WSM for the 348 and seems to recomend "Agip anti freeze" not Glycosheel

Just looks like any other antifreeze does anyone know if it is good, bad or otherwise...?

http://www.agip-q5.com/fileadmin/FILES/antifreeze_extra.pdf

 

I use BMW coolant which was designed for aluminum engines...

 

I have been using dexcool for ten years now change every year with distilled water no problem whatsoever. on the inside of the aluminum pipes just the slightest coating of white material. Comes out red & clear as a bell every year I always wanted to try evan collant but never got the balls to try it....

Rob
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Dear Ferraristi,

Two years?

I change the coolant in my 91 Testarossa every year.....yeah, it's a pain too !

I drain the rads and both drains on each side of the block. I refill with prestone engine flush with distilled water. I bleed the system, drive for a few days and drain all over again. I then refill with prestone (green ) coolant 65/35 distilled water ( best cooling performance...as noted on back of container ) and bleed the system all over again.

When I bought the car about ten years ago, you wouldn't believe the crud that came out....orange water ! . Now, after the flush with only distilled water being done every year, you just get a very light green ( coolant left in the heater core...yes turn it to full heat when refilling and bleeding ) water. Even my 4 year old expansion tank ( stupid design made of steel ) is clean inside.

BTW, I change all fluids, filters, plugs once a year...except the gear oil....3 years.

...no, I don't wear my white Miami Vice linen suit while working on the TR


Shamile

Freeze....Miami Vice !

 

You get better freeze resistance at 60/40 and probably 63/35. Use judgement for your area.

 

Correct. The freeze protection improves until about a 70:30 mix of glycol:water and then the freeze point increases. The issue one will face with higher ratios of glycol is that the heat capacity of the mixture is lower than water. So the heat removal efficiency is lower. Now this isn't normally a problem unless you live in a warm area like Arizona, Florida, Texas, etc. I would recommend using the blend ratio that gives the appropriate freeze protection while using as little glycol as possible. The 50:50 mix generally recommended is a good ratio for nearly all areas of the US as it will protect to about -35 F.

 

Dear Ferraristi,

Thanks for the clarification guys.

Parkerfe, I know about GA...if you look at my title listing when I post, you will notice that I live there too. (Lake Oconee GA ) Going back to the lake from work, I would pass the bank signs in summer....106 F !

So...it seems higher coolant ratios are for better freeze protection, not more efficient cooling. I will go to 50/50 on my next change....due in a couple of weeks.

You always learn something new....even when you think there's nothing new on the subject to learn.


Shamile

Freeze...Miami Vice !

 

How bad is the corrosion issue with the brass radiator and aluminum radiator? If you could switch to an aluminum radiator that was the same size as the brass one would it be worth it?

 

IMO yes make the switch. Al can last longer. However, with regular service, flush and fills with the appropriate protection package you should have no problems. Al corrosion protection is from silicate while yellow metal like brass needs an azole chemistry.

Unless your current radiator is failing, I would stick with what you have. Make the change when it is cost effective to replace a failing core. I don't know for sure, but it seems like all new cars and after market radiators are aluminum core types.

 

The best thing ever was the copper/brass core radiator since they were easy to fix. You could rod them out add rows solder headers. Aluminum is very difficult although if you have a core leak you can solder them with a special very low fusing aluminum solder but the header tanks are usually plastic. The header tanks fail all the time on these. Cooling efficiency is better with Al and Al is lighter small gains for a crappier overall part. Why do this well you make more money selling radiators than fixing them like selling premixed 50/50 coolant for 10 bucks and 100% coolant you have to add water yourself for 12 bucks. Who buys 50/50 premix? How stupid do manufactuers think we are?