Millers Oils Extra Cool Radiator Coolant

One of the biggest concerns of hardcore Honda enthusiasts with modified Hondas is that of ensuring sufficient cooling for the engine. When some serious mods are done to the engine in the quest for more power, a matching upgrade to the cooling system is mandatory. Upgrades to the cooling system includes things like an upgraded radiator. For example, I myself am using an aftermarket aluminium radiator taken off a 'track car' (car built for use on race tracks). Many uses a 'high pressure' radiator cap, e.g. a Spoon or Mugen 1.3bar radiator cap. Finally, the use of a good radiator coolant is very crucial to complete the cooling system upgrade.

Honda strongly recommends that coolants used should comply with their own 'HES' or Honda Engineering Standard code D-2009-75. Unfortunately, due to the very specific nature of this 'standard' and the fact that Honda has been steadily losing its clout and prominence in the enthusiast scene, few if any aftermarket manufacturers today will bother to comply with HES. This effectively means that if one is to be adamant that any fluid - coolant, lubricant, etc be HES compliant, then basically the person is practically limited to using only original Honda made items. This is fine actually as in general Honda's own coolant, engine oil, and so forth are very good and gives excellent results. However, with hardcore enthusiasts and modified vehicles, the thing is our Honda will exceed the limits of Honda's products. For instance it is the physical law that when we produce more power, we produce more heat. Beyond a point, the stock Honda coolant can no longer do the job.

I have been using Honda's original radiator coolant all these while due to concerns about compatibility, especially with the aluminium engine block. I have seen a lot of engine internals and especially radiator insides and caps with white deposits and corrosion which are the results of using incompatible coolants. These deposits can block the coolant passages inside the engine blocks and worse, jam the water pump and similar nasty stuffs. But like many hardcore enthusiasts, I have since outgrown the cooling ability of my stock system. Currently my problem is compounded by lack of space inside the engine bay which prevents me from using proper radiator fans. So the cooling problem manifests itself by a steadily increasing water temperature in bad traffic jams during very hot weather conditions. The frustrating thing is cooling in all other conditions, including extended WOT runs are no problem. This then is the background to me foraging into the use of aftermarket coolants.

There are actually many aftermarket coolants around and many of them really do work. The one that I am currently using is Millers Oils Extra Cool, passed to me for evaluation by Millers Oils distributor Cosmic Elite. Millers Oils markets Extra Cool as a corrsion inhibitor besides being a coolant and claims that it 'improves laminar flow' which increases coolant efficiency to reduce the water temperature by up to 15°C. In addition, the one property which caught my attention was the claim that Extra Cool offers corrosion protection for all metals found in engines e.g. aluminium, magnesium, cast iron, etc. This is a very important factor as I noted in the previous paragraph. I was given one 250ml bottle of Extra Cool which can treat up to 10litres and I added the whole bottle into my radiator. Extra Cool itself is pale yellow in colour and after adding, will also turn the radiator water pale yellowish as well.

In use, I have found Extra Cool to be quite effective for my situation. With the stock Honda coolant, my water temperature will steadily climb during very bad & slow traffic jams in very hot weather conditions. This is due to the weak air-flow generated by the smaller than ideal radiator fans. When the traffic jam duration exceeds half an hour, my water temperature can touch 120°C. While some may consider running at such a temperature to still be OK, understandably I would very much prefer to have a lower water temperature under such circumstances.

In this area, Extra Cool has managed to keep my water temp under such circumstances to below 100°C. My water temp guage is analog so I can't confirm if my water temp runs 15°C lower as claimed, but I can say that visual estimation suggests it is around that figure, i.e. instead of hitting 120°C under very bad traffic jams in very hot weather, I am now hitting around 105°C instead. In fact, during the half a year or so that I have been using Extra Cool, I have only encountered one particularly bad traffic jam during a particularly hot day where my water temperature exceeded 110°C. I can happily say that I have not encountered another occurrence where my water temp hits 120°C since. In this area, for me personally I can say I am happy that Extra Cool delivers what it promises.

The other concern is in deposits and corrosion. In this area, I have been diligently checking the radiator cap as well as the areas where the radiator hose connects to the radiator and engine block. As there is no easy way to check the internal coolant passages or the water pump, short of taking the engine apart, this is the best way I currently have of ensuring that Extra Cool does not cause any nasty deposits buildup, like one of the coolants I used in the past. Thus far, after half a year of usage and probably over 10,000km mileage, I am relieved to see a completely clean radiator cap. The inlet which the cap clamps to is also clean and the water itself is still transparent pale yellowish in colour. In this aspect, I think Extra Cool is not causing any deposits buildup as from experience, I know for a fact that gooey whitish deposits will clog the 'neck' and line the radiator cap after just a couple of months of usage.

So for TOVA readers who are in a similar situation like me, I can suggest that you check out Millers Oils Extra Cool for possible usage on your car. Of course I will only recommend that you check and possibly test it out. But I would also recommend that you carefully monitor for its effectiveness, especially for signs of unwanted deposits as best as you can. Nevertheless, if Extra Cool works as well for you as it does or me, then I would think that you too would be delighted at its usage.

All opinion expressed here are from experience. Your results will vary according to your own specific conditions. To get contact information for Cosmic Elite, Malaysian importer for TORCO and Millers Oils, click on the TORCO banner on the main page of this website.