There is usually a greater risk attached to buying aftermarket components compared to the same product when fitted to the car as original equipment (OE). This is because automotive manufacturers spend a lot of time and money to conduct endurance testing on all components and accessories fitted to their cars.
Most accessory manufacturers cannot afford to do the same amount of testing with the result that their products are often inferior. These remarks apply equally well to small accessories and large ones such as an air conditioner system. It’s especially important not to listen to sales talk because the salesman has only one aim in mind: to sell you something.
Buying fuel-saving devices
A modern car is the result of a great deal of research, some very sophisticated design procedures, high quality production techniques, thousands of hours of full-throttle dynamometer runs and millions of kilometres of road testing under extreme road and weather conditions. As a result the manufacturer knows what is best for its vehicles, and publishes this information in a workshop manual and an owner’s manual.
However, as soon as a new model appears, aftermarket additives and gadgets flood the Internet, promising unbelievable improvements in fuel consumption, performance and engine life. Not surprisingly, most of these products are not worth buying.
These products fall into various categories:
1. They don’t work and may harm the engine or some other component
2. They don’t work but are harmless
3. They appear to work, and then fail after some months
4. They work, but will reduce engine or component life in the long run
5. They work, but do not live up to the advertiser’s claims
6. They perform as advertised
The last category is the only one worth looking at, but very few products fall into this category. There is usually some reason or another why the seller’s claims can be ignored.
How one can spot bogus products:
1. They usually claim improvements of more than 10%. Engineers know that any improvement of more than a few percentage points is just about impossible.
2. They offer pseudo-scientific explanations as to how and why the product works. The terms used will often baffle a scientist, let alone a member of the public. I’m often given explanations of this kind, and it makes my day, because it’s great fun to tie the salesman in knots by asking him to explain his fancy words.
3. They claim to solve problems that don’t exist, or conditions that are better fixed by going to the root cause.
3. Ask the salesman why such a fantastic product is not standard equipment on a new vehicle. He will usually tell you one or more of the major automotive manufacturers are evaluating it. Your answer should be that you’ll buy the product as soon as a major manufacturer is also using it.
Wrong advice by mechanics and “expert” members of motoring clubs is another source of confusion. For example, it is very common for mechanics and workshop foremen to tell motorists that the owner’s handbook recommendation to change engine oil every 15 000km is wrong. They will then claim that the oil should be changed more often, at say 10 000, or even 8000 km. The truth is that there are at least three good reasons why this advice is out-dated:
1. Modern oils are far better at lubricating and conducting heat away than oils of 15 years ago.
2. The oil stays cleaner because the adoption of fuel injection has resulted in an engine running much closer to a chemically-correct mixture for most of the time.
3. The change to unleaded fuel also keeps the oil cleaner for longer.
A great deal of car talk is based on anecdotal evidence, meaning it has not been scientifically proven. The advice to add some two-stroke oil to diesel fuel is an example of anecdotal advice. Some people add this to aid the fuel’s lubricity, but there is already a lubricity additive in the fuel. It was put there by the oil company, so, by adding diesel, you’re trying to solve a problem that doesn’t exist. In addition, some two-stroke oils may contain a chemical that will contaminate the catalytic converter.
Modern oils are so scientifically blended that aftermarket oil additives also belong to the category of products that are trying to solve a non-existent problem.
My advice is: stick to whatever the owner’s manual recommends.