Waterless Coolants (again)

We wrote some time ago that we did not favour the use of so-called waterless coolants, on account of price, and the temptation to try to fix a cooling problem by just changing the coolant. Here is our previous article: https://www.kwecars.com/jaguar-tech-centre/waterless-coolants-our-view/

We must now go further and strongly urge owners not to allow well-known waterless coolants to be used in their road cars. We recently had a Daimler Double Six in with serious over-heating which was very difficult to diagnose. New radiator, thermostats, fan, and careful bleeding had no effect. The owner was adamant that we must not change the waterless coolant, and that he used it on all his cars – many of which were used in racing.

However, deeper investigation showed that this coolant was creating gelatinous globs in the cooling system which was reducing flow, and thus engine cooling. We sampled some of this goop, and it behaved like a 70’s lava lamp – horrible!

Once we had flushed it all out thoroughly and replaced with our preferred OAT long-life coolant additive in plain water, the over-heating disappeared, and all was well.

The instructions for this waterless coolant are clear that the existing system must be completely cleared of old conventional coolant, and they even supply a pre-coolant fluid which is supposed to in some way aid the removal of the old stuff. But the bottom of the cylinder block can never be flushed out – it is well below the level of any access ports.

We can see that in a completely dry engine and coolant system flow-reducing globs will not form, but even the website warns that the engine will run hotter when using waterless coolant, which rather defeats the object. And the reason for this is that the glycol-based coolant is a lot more viscous than water, and cannot flow well through conventional radiators and heater matrixes. Indeed, the relevant website recommends replacing the radiator for one with larger internal channels.

This is clearly not achieving what any classic road-car owner would want, and indeed could seriously damage an engine through overheating.

The only benefits we can see in using this product – in a modified cooling system – is that it will not allow corrosion, and will allow much higher temperatures in the coolant before it ‘boils’. But no road car can get anywhere near this increased max temp (claimed to be over 150degC) without there being a very serious cooling fault (e.g. rad fan not spinning) which should of course be fixed!

Further research shows us that this type of coolant is wholly inappropriate for road cars, though we can see the application in a race car where the engine is often designed to run very much hotter than a road car.

Finally, it is vital – especially on the Jaguar V12 – to renew the coolant every 2 or 3 years with conventional blue/green/yellow anti-freeze or 5 years with red OAT anti-freeze. And even in hot countries where the outdoor temp never gets near freezing point, one should still change the coolant routinely since it is the anti-corrosion additives in ‘anti-freeze’ which are needed.