Fuel, coolants and speed

Hi Baraza,

Thank you for the good work you are doing.

Now to my questions: 

  1. I read sometime back about the Total Challenge and that the winner covered the distance from Naivasha to Nairobi using less than two litres of fuel. How did they manage that? Were any modifications made to the car?
  2. What is your advice on the use of car coolant in the radiator. Must it be mixed with water or can it be used alone?
  3. Between what range should one maintain a car’s rpm  while driving on the highway in order  to have maximum economy on fuel.

Freddie

Hello Freddie,

  1. No modifications were made to the car. In fact, the rules specifically call for bone stock, factory-spec cars. The only mods allowed are small adjustments such as weight loss by discarding things like tools, passengers and spare tyres, but you can’t remove the seats and upholstery or any of the car’s equipment like the AC, which is a considerable lump of deadweight on its own. One can also tape-up panel gaps, scoops and intakes to optimise aerodynamic efficiency by cutting down on air resistance. Other than that, it is you, your brain and your right foot. Extreme hypermiling driving skills are called for, some of which are dangerous to both car and driver, such as tailgating trucks, coasting with the engine off, avoiding all braking until absolutely necessary or driving with extremely low engine revs. It takes a special kind of skill to achieve this, and the mental effort that goes into it is insane. It is a lot tougher than, say, driving a sports car up to and beyond 260km/h.
  2. Thanks for asking about coolants again, because I have a clarification to make about something I wrote last week. I said that it doesn’t really matter what colour coolant one uses, and I was right. However, insistence on my apparent wrongness from certain quarters has led me to specify what the colours mean.

Coolants all contain antifreeze and corrosion inhibitors (which is why I said one can use any colour: they all serve the same purpose anyway). The difference comes in the ingredients in their respective recipes. They are all based on ethylene glycol, which is the active antifreeze (as all alcohols are, which is why some people use vodka to thaw out their tyres in extreme cold condition driving). The green antifreeze uses a cocktail of silicates, phosphates and borates, which make the solution alkaline and thus prevents formation of acids which accelerate corrosion. It has a short lifespan.

Red/orange antifreeze mixes the same ethylene glycol with organic acids such as nitrites to achieve the same effect, but it has a much longer lifespan and will work over a wider range of temperatures, which is largely irrelevant to us who live within the tropics. Word on the street is not to mix these two coolant types unless one has done a full-system flush beforehand because the presence of silicates that prevent aluminium corrosion in the green coolant type is incompatible with the nitrite-based organic acids in the orange coolant. Beginner’s chemistry: the alkaline silicate mixed with the acidic nitrites will just react to form salt and water (acid + alkali = salt + water), which is kind of defeating the whole anti-corrosion intention of these coolants.

As stated last week: for best results, mix coolant with water in equal parts (1:1 ratio) for radiator use. Also, try not to drink it even though the name suggests alcohol mixed with sugar. It isn’t alcohol and sugar at all, it is poison.

  1. Keep the revs below 2500rpm for a petrol engine and below 1600 rpm for a diesel engine and you’ll be fine. However, this might not be practical for some cars. If you drive a Type R Honda, an S2000 or a Mazda RX8, then you will need to rev their nuts off because these engines are designed to rev all the way to 9000rpm to develop any real power and the torque is either little or hidden away in the top shelves, somewhere in the region of 5000rpm. Driving below 2500rpm will be frustrating; but then again these are sports cars that pay no attention to the importance of fuel economy..

______

MEA CULPA

sorry folks! I got it wrong on Total Lubricants… and that bit on coolants

Baraza, in your advice to one May Clarkson in last week’s Car Clinic, you said that you did not know anyone who recommends Total lubricants. Well there are! Lack of information (read ignorance) doesn’t mean that such recommendations don’t exist.

In Kenya, Total supplies (and you are free to confirm this claim) lubricants to DT Dobie, Toyota, Nissan Kenya, Subaru, Simba Colt, Scania, and AVA (factory fill for all Hino Trucks) among others. Talk of confidence by local Original Equipment manufacturers (OEMs)! Regarding lubricants, especially in relation with OEMs, the words “prefers”, “recommends”, “approves”, etc have a strong meaning.

A word of advice to May Clarkson with reference to the Nissan X-trail NT 30 automatic. When it comes to ATF oil change, be very cautious about the fluid you use. It has to meet Nissan Specs: Nissan-matic D,K,L. etc .

We have the ATF in our range that meets the specs – Fluide XLD FE. I bet you will say it’s French patriotism, but it meets the specs of other OEMs that are not French.

On coolants, you missed some facts when you said it must be mixed with water; a number of coolants in the market are ready to use, or pre-mixed, for that matter.

Oliver Biyogo

Lubricants, technical and training manager, Total Kenya

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