lifetime coolant?

There was a good article linked from either here in Tech or 308 which explained that the best coolant to use is dependent on the materials in your cooling system. The takeaway: old cars with brass radiators are best served with green coolant.

 

It really depends on your definition of "lifetime" now doesn't it?

Oil change interval is frequently 10K miles or more but I would NEVER recommend leaving it in there that long.

 

Traditional flourescent green for cast iron engines is fine. For old alloy engines, I would go with G05. It's been used by MB for decades.

 

Contamination, (particularly fuel and coolant) is always a risk. At least annual oil changes are common sense. If you want to skip something, the filter can probably go two changes.

In my opinion, the car's manufacturer doesn't have the same priorities as the buyer. They ultimately want it to wear out eventually. Once the warranty period has expired, you're on your own. If a head gasket fails or a fuel injector leaks and you drive it around for 10K with diluted oil, the bearings won't like it.

 

Coolant (the glycol) remains fine for long periods of time, what does happen is that the additive package (acid netralizers, corrozion inhibitors) are consumed over time protecting the engine. Once the additive package is done, it really is best to change it out.

Plus, I don't think BMW really means lifetime when some of us keep their cars 15-30 years.

 

Very true.

A great deal of effort is concerted by car manufacturers to arrive at "factory maintenance schedules / recommendations" that are the ideal balance between ---- no big problems while under the warranty period vs. allow it to blow itself up ASAP after the warranty period (i.e., so they can sell customers another unit) .

 

Here's my $0.02 on the idea of "lifetime" coolant.

There ARE coolant formulations that can indeed last a very long time if they are in the right exposure and environment.

However, it is the system itself that has the shorter life span. In a car, I am strong believer that the coolant circuit itself needs to be mildly "flushed" every now and then to remove particles, contaminants, residues, etc. that accumulate over time from normal operational use ---- this occurs regardless of what coolant is used (even if it is purified water). Since the coolant needs to be emptied in order to do this, one might as well replace it, too --- either that or filter / purify it for re-use, which is rather impractical to do. Even though the used coolant itself may be fine in terms of its chemistry and thermal performance properties, it does still get contaminated --- so it needs to be de-contaminated or replaced (again, replacement is far easier and cheaper).

So how often ? How long before coolant needs to changed / system flushed ? That depends on several factors. By far, you will get the most longevity by running a very high quality coolant in an all-aluminum system. Which is why modern cars from makes such as BMW, Mercedes, etc. say their coolant (and systems) are good to go for "lifetime".

However, all older cars (and still many newer ones) have a mixture of materials used in their systems which are exposed to the coolant --- aluminum, brass, copper, iron, steel, etc. It is the nature of the high heat and electrolytic properties of the coolant that causes issues by common exposure to these dissimilar metals ---- not even the best coolant can last a "lifetime" in such systems. The systems need to be periodically flushed and the coolant replaced --- and not just because the additives have been used up, but because the coolant has become irreversibly contaminated, and therefore it has lost a significant amount of its performance.

Moral ?

I can't give hard time / mileage tables. However, TIME is far more important than mileage.

But, if I had a brand new, "maintenance-free", BMW with a "lifetime" coolant system, I might be tempted to run that car for quite a while (5, 8, maybe even 10 years? ) without changing the coolant / flushing the system. But, in an older car, or any car with a "mixed-materials" system, I'd choose not to go more than 2-3 years without changing coolant and not more than 3-5 years without flushing.

Also, putting super-high-end, $$$, "lifetime" coolant into an older / mixed materials system is a waste of money ---- because it will not last much longer than the regular (cheaper) stuff, anyway.

FWIW

As an aside...... whenever someone tells me something is good, guaranteed, etc. for a "lifetime", my standard response is always the same ----

Which "lifetime" ???? Yours, mine, or the product's ?

 

Or the lifetime of the company that guarantees the product.

 

Yes it does. I had a new 100kW diesel emergency power genset eat through its brass radiator in 6 years. Gen tech said to change the (green) coolant every year or this happens. It had a row of pin holes in the upper rad tank right at the water line. That incident changed my opinion on coolant changes 180 degrees immediately.

 

This subject is of great interest to me. I have a 1978 308 with about 150K miles on it. I have been updating original parts and systems on it for several years and I am chronicling the updates on my site, MMRsite.com

I recently completed a six part story about upgrading the cooling system. This included a change in water pump, hoses and to an aluminum radiator. When it came to coolant I was advised to use Zerex "original" Formula "low silicate" green. The local Napa store had to order it for me. Then I learned about a non-water system called Evans Coolant, made in Connecticut. There is an interview on Jay Leno's site with a representative of the company. The stuff is not cheap but they claim it never requires changing. I like the premise. I am also advised that several new car manufacturers are specing it. Does anyone have experience or thoughts about Evans Coolant?

 

A buddy with a sailboat just put Evans coolant in his system for the diesel motor.
So too soon to tell, but he says she runs cool now-
Apparently big rigs are starting to use it, and it is expensive, like $500 to do a big rig,
but lasts forever, has an insane high boiling point, and does not have water in it.......

 

There are a few threads here on Fchat about Evans.