Coolant Question - thoughts?

[Tubbs76]

Hi all,
As all of us VR6 owners know, our little engine bays can run hot. More so started thinking recenty about coolant (petrol vehicles) v coolant (diesel vehicles) and how they differ.
Diesel vehicles normally run hoter and under load and my understanding is that the coolant they use as a resut is stronger to help cool.
In theory, wouldnt this mean that if you used diesel coolant in your car, the cooling efficiency would improve somehwat? If this actually works or not is another story.
My only concern is that seeing the coolant is stronger, it could wear out things like water pump seals quicker than standard coolant.
Anyone tried this before or any thoughts? Thought id put it out there

[Diesel_vert]

More so started thinking recently about coolant (petrol vehicles) v coolant (diesel vehicles) and how they differ.

Diesel vehicles normally run hotter and under load and my understanding is that the coolant they use as a result is stronger to help cool.

In theory, wouldn't this mean that if you used diesel coolant in your car, the cooling efficiency would improve somewhat? If this actually works or not is another story.

I don't think manufacturers specify different coolants for petrol and diesel engines in passenger cars.

My only concern is that seeing the coolant is stronger, it could wear out things like water pump seals quicker than standard coolant.

I would think that a higher concentration of additives or inhibitors would actually offer increased protection, so long as they are compatible with all the parts and components of the engine.

Anyone tried this before or any thoughts? Thought id put it out there

Most coolants for passenger vehicles are a mixture of water (H2O) and ethylene glycol (C2H6O2) plus various additives, inhibitors and dyes. Ready-made or pre-mixed bottles are usually sold as a 50/50 mix of ethylene glycol and water.

Water is very effective at transferring heat because of its high specific heat capacity (able to absorb a lot of heat) and low viscosity (free & fast flowing), but it has a narrow operating range (useless below 0°C or above 100°C - though the pressure of the vehicle's coolant system increases the boiling point somewhat) and is not kind on bare metal parts and components.

Ethylene glycol increases the freezing and boiling point of water, but has a lower specific heat capacity (absorbs less heat) is more viscous (affects heat transfer) and is also not kind on bare metal parts and components (just like water).

Additives and inhibitors are necessary to protect metal surfaces from corrosion, rust, scaling and other nasties.

Dyes can be used to indicate types of coolant, but can also be completely arbitrary and is not a reliable tell-tale, especially for modern cars.



A coolant with either too much water or too much ethylene glycol will compromise engine operation. Therefore, it is best not to stray too far from the manufacturer's recommendations.

You could increase the ethylene glycol ratio to 60% in very cold climates (any higher would start to affect heat transfer), or decrease it to 40% in very hot climates (any lower would start to affect corrosion protection), but a 50/50 mix will be fine for most cars in most climates.

I think the proper (albeit expensive) way to increase the cooling capacity is to upgrade the radiator or increase the system capacity/pressure (or something along those lines), rather than messing about with coolant mixtures.

[Umai Naa!!]

Diesels typically run cooler due to greater thermal efficiency.

[The One]

VW currently recommends G12++ on all PETROL and DIESEL models (bar those requiring AdBlue ofcourse)

Enough said.

[Tubbs76]

Agree. A better performing radiator is def the way to go. I'm in the process of sourcing a high performance Aluminium one as well as upgrading the oil cooler. ive just received my mishmoto silicone hose kit which I'm sure will help somewhat.
I'm also sourcing ford xb gt bonnet scoops to graft into bonnet to help with cooling while driving and heat dispertion while idle.
My question re coolant is more a theory based question. In theory, should cool better...

[Diesel_vert]

My question re coolant is more a theory based question. In theory, should cool better...

I wouldn't expect it to.

I suspect coolants for heavy-duty or commercial diesel engines may have a higher dosage or concentration of various additives and inhibitors (maybe even unique), but that doesn't affect the coolant's heat transfer properties.

The heat transfer mechanism in coolants is driven by water and ethylene glycol, usually at a ratio of 50/50. Additives and inhibitors only account for a small percentage of the total volume (usually 5% or less).

Given the same ratio, there will be no change in the coolant's capacity to transfer heat transfer unless you change the compound (e.g. methanol, propylene glycol, glycerol, etc) and I don't know if these compounds transfer heat any better than ethylene glycol does.

So again, I have my doubts on whether coolants made specifically for diesel engines will transfer heat any better.

[mb1907953]

I wouldn't expect it to.

I suspect coolants for heavy-duty or commercial diesel engines may have a higher dosage or concentration of various additives and inhibitors (maybe even unique), but that doesn't affect the coolant's heat transfer properties.

The heat transfer mechanism in coolants is driven by water and ethylene glycol, usually at a ratio of 50/50. Additives and inhibitors only account for a small percentage of the total volume (usually 5% or less).

Given the same ratio, there will be no change in the coolant's capacity to transfer heat transfer unless you change the compound (e.g. methanol, propylene glycol, glycerol, etc) and I don't know if these compounds transfer heat any better than ethylene glycol does.

So again, I have my doubts on whether coolants made specifically for diesel engines will transfer heat any better.

This is a great post. You have to look at the thermodynamic properties of the fluid being used and I highly doubt that a slight change in concentrations will have a dramatic effect on the specific enthalpy of the coolant. You would benefit more from changing the thermostat in the car so you run at maybe 80C instead of 90. But this affects warm up and whatnot. Just changing the fluid isn't going to have a massive affect on the temperature your car runs at.

[KKK VR6]

What oil are u using now ?

[Tubbs76]

What oil are u using now ?

I am currentkly running 10w 50 Penrite fully synth. Just stsarted running it about 3 months ago. Prior to that have always used mobile 0w50 fully synth. Thought id change and se if any difference, as far as i can tell, they are both as much as much.
Thought of changing to a lower temp thermo but like Diesel Vert says, effects warm up, etc. so lt it be. I have no doubt once I source a good aluminium radiator and oil cooler, I should see noticable imporvements in cooling. I am sure the bonnet vents will make a slight difference also.