Anyone else running a lean coolant mix?
 

I had always heard that ethylene glycol has a poor specific heat compared to water. Recently, I found this source confirming the reduced heat capacity of glycol solutions:

http://http://www.engineeringtoolbox.com/ethylene-glycol-d_146.html

So, when I flushed my system out recently after changing to a low temp. thermostat, I mixed up my brew with only 25% Porsche OEM glycol + 12 oz. Red Line Water Wetter + Water.

My test on this mixture indicate a freeze point of about 7F, which should be more than adequate for garage storage in Georgia, and a 14 psig pressure boil point of 258 F, which is only sacrificing about 4 F from the 50% solution pressure boiling point.

I searched on here, but did not find where anyone else was doing this. As I recall, most racing rules require 100% water for ease of track clean-up, but where there are no sanctioning rules to meet, I believe a lean mix is the way to go if your cold weather and storage conditions will allow it.

I thought about doing that too, but I decided against it. I too have low temp therostat so my car doesn't have an overheating problem in any condition, so the lean mix would really not help. And the downside to the lean mixture is that the anti-faoming, lubricant and other additives aren't at the proper levels, possibly causing longevity problems with the cooling components.

One consideration could be that the temp sensor is measuring temp at its particular location and is an average. The vicinity of the combustion chambers will be hotter. If localized boiling occurred then heat transfer would be diminished. There could be a negative feedback loop.

I've read on this forum that Box oil temps are well into the 200s - much higher than the ~180F indicated coolant temps, and ofcourse these 2 fluids meet at the oil cooler.

Yeah, H2O has higher heat capacity than EG, so if you were designing a car maybe you could take advantage of this with a smaller volume. But the Box is done and has a proven track record, so why mess with it?

What you have done is increase the freezing point of the mixture, reduce the level of corrosion protection, shorten the life of the coolant mix, and throw in a useless additive that may further shorten the life of the coolant. I’d also bet you did not use distilled water either, which further exacerbates the shortening of the coolant mix life.

I’m not really sure how any of this is a positive……………

Sounds like someone is mad that it's too cold in their area to run a mostly distilled water mix, lol. I ran this sort of mix for nearly a decade in the dirt bikes I raced with no problems and excellent results. I also run a very similar mixture in my boxster. The Water Wetter adds corrosion protection and reduces the surface tension of the water. If I'm not mistaken it's actually not too far off from dishwasher soap. If you're not seeing freezing temps, or pushing the car close to the point of boiling regularly, this is always a good mod to increase your systems cooling capacity. We all know that glycol doesn't transfer heat very well compared to water. This is also more environmentally friendly as you're using less of the toxic stuff.

"Water Wetter" is a cheap mix of surfactants that has been shown to often both lower the corrosion inhabitation of the OEM coolant, and then die off fairly quickly itself, leaving you with little, if any, corrosion protection. It was originally marketed in competition environments to lower the surface tension of pure water, which is fairly high as the molecule if extremely polar. Then the manufacture started marketing it as an additive for street cars (a much larger potential market), where unfortunately the coolant mix already has a fully chemically compatible and long lived surface tension modifier additive package of its own that obviously does not adversely react with the coolant package. Add in the fact that most people running pure water are doing so for other reasons (e.g.: race tracks hate anti freeze spills) and also tend to drain and refill they systems more frequently; and its utility on the street becomes even less obvious. A race car often has a cooling system fluid change several times a season, if not after every event.

Moving away from 50/50 coolant mixes to gain a heat transfer advantage is also somewhat of a fools errand because the real world actual differences are extremely small. You would gain a substantially greater degree of heat transfer capacity by going to a 160 degree thermostat and adding a third radiator of the car does not already have one.

The primary results are that the “lean” coolant mix needs to be changed more frequently, it will degrade the capability of the limited amount of coolant used, and could end up reacting with it in a way you did not expect; hardly an economic benefit in a car that is a pain to change the coolant in unless you have the vacuum charging system, which not everyone does. You might also be surprised how quickly the inside of one of these cooling systems gets nasty running a “lean” mix or only water and one of these "snake oil" surfactant mixes…………

Wow, I had not expected such a negative response to this concept. You would have thought I had criticized Mobil 1 or something.

Anyway, this mixture has been used successfully in my sport bike for about 10 years, and in both of my BMW's for the last 5 years.

Prior to that I ran a Lola S2000 class race car for 6 years with water and Water Wetter only, and no glycol as required by racing rules. Back then you could only buy Water Wetter from Pegasus Racing or someone like that.

Water Wetter is a surfactant that allows the liquid to better wet the surface for heat transfer, as water has a naturally high surface tension factor, and needs help in this regard. Red Line makes some good products including Water Wetter, and I take exception to anyone characterizing this as a "fools errand"

I don't believe Water Wetter offers any corrosion benefits, and for that I am using the real Porsche glycol solution - just in a lower concentration. I change my coolants out every year or two, so I do not believe this is a problem.

If you really understand the data, it is obvious that glycol sucks as a heat transfer fluid. The only real thing that it has going for it is in depressing the freeze point. So, I will be using the least amount of this junk that I need to in case my garage heater craps out.

You may choose to do otherwise...

Speaking as a chemist, EG both lowers freezing point and raises boiling point - 2nd law of thermodynamics. That is a fact. Also, the Box radiators, being Al, do not need a wetting agent versus water. I suspect that is a gimmick here.

What to me is a question is, when you say you've used the redline stuff "successfully", what does that mean? Aside from track rules, you could not have used 50/50 EG/H2O successfully? Also, given that H2O has higher heat capacity than EG, doesn't that mean you need to both utilize that added heat capacity (ie bigger engine) as well as dissipate the added heat more effectively (more radiators, fans, etc)?

You can take it any way you want, but Red Line, and other small boutique “blenders”, have been pushing products with questionable “advantages” often based more marketing hyperbole then technical facts (RL and another similar company were called out on the web more than once for claiming they have lubricant products “approved for applications requiring ACEA ratings"; only problem is that the ACEA says they have never submitted their products for any of the mandated independent lab testing protocols, so they can’t possibly be “approved”).

In a laboratory, the total “improvement” in heat transfer from the addition of this and similar surfactant mixtures is marginal at best; and even then is only temporary as the surfactants quickly break down. On a fully instrumented engine tests, the level of improvement when the mixture is fresh is so small as to be considered insignificant, and then goes away completely when the surfactants start to deteriorate. For short runs in a ten-tenth’s racing application, it may provide some very small level of improvement, but again, no where near what you would get from reducing the engine’s “steady state” coolant temperatures by using a lower temp rated thermostat, and/or adding additional heat transfer surface area with a third radiator; both of which are far more capable in altering the coolant’s heat transfer capability, do not quickly break down with use, and do not need to be replaced regularly. There have also been posting on VW and Audi related websites noting that the RL product has demonstrated some pretty adverse reactions with the G12 coolant they use, which is chemically similar to Porsche’s OEM coolant.

In the end, it is your car, and you can do anything you want with it; but in the case of the how useful this additive is, used in conjunction with an overly diluted coolant mix in a street application, let us just agree that we completely disagree...............

I've often thought about this and I'm glad that its come up for discussion...

I haven't tried it because I haven't seen any need for more cooling capacity, even during long track days in the desert when its 105F+ and I'm driving the car at near-continuous redline, the temp gauge never even gets to 200F.