Idling Your Car Before Driving – Good Or Bad

Nov 11, 2019 | Articles, Idling Your Car Before Driving – Good Or Bad

Idling your car before driving off.

Idling one’s car for a few minutes before driving off, is still an unchanging ritual with some vehicle owners. Old habits can stick. The previous generation taught us to warm up our engines by idling it before setting off. But why? Is this practice a good or a bad practice, and is it still valid for today’s engines? In the distant past, engines were still primitive. Materials were not as advanced as they are today. Manufacturing tolerances were less precise than nowadays, thus the idling of a cold engine may have held some benefit. However, with the progression of engine technology, any advantage was soon displaced by the disadvantages of idling cold engines. We will come to these disadvantages shortly.

The Alfa-Finger in the Pie

Before we get to the disadvantages, let us first deal with Alfa’s contribution to the topic at hand. Why did Alfa Romeo advise drivers to idle their engines for a while before driving off? The reason is simple and innocent enough. The twin-cam Alfa engine, back in 1954, was a very modern engine for its time. Do keep in mind, aluminum cylinder block technology was still in its infancy when Alfa launched this famous engine. Sensibly, they used iron cylinder liners as a durable wear surface. The hard aluminum-silicone alloy cylinder blocks we use today was still undeveloped then.

Aluminum and iron do not have the same expansion coefficients when it heats up. The Alfa engine’s iron liners would physically be too long for the contracted cylinder block when cold. The result: sleeve distortion. This would only go away after warming up the engine. If you work the cold engine too hard, it can cause excessive wear. For this reason, Alfa prescribed idling the engine before setting off. This stuck and car owners followed suit.

The carburetors!

According to an article written by, the carburetors carry partial blame for the idling ritual. According to them, carburetors need time to heat up to work efficiently. This contributes to the idling phenomenon, a problem they call “a bad habit that could unknowingly damage your car”.  You may read more about this article here.

The disadvantages of lengthy idling

It is said that leaving your engine to idle for too long, can cause engine oil dilution. This is when raw fuel seeps into the oil, breaking down its lubrication properties which can turbocharge its wear. To be clearer, excess, unburned fuel that mixes with engine oil in an engine crankcase, cause engine oil dilution. According to, the belief that it is beneficial to idle your car before you get going is a myth. They say that it doesn’t help anything if you let your car’s engine run in such a way. According to them it just wastes gas and pumps out needless fumes. You might just as well get on your way. If you wish to read more about this article, click here.

The idling of cold engines

Cold engines require rich petrol-air mixtures to run properly. The reason is that the cold combustion chamber impairs the proper atomisation of the fuel particles. This causes more fuel to condensate on the cylinder walls. This fuel-condensation tends to wash the fine oil layer off the cylinder walls, thus increasing wear. It, therefore, follows that running cold is the worst thing an engine can do. It would be equally bad to work the engine hard while it is in this state. Because it is not doing any work, idling is also by far the slowest way to warm up an engine. It should be brought to its operating temperature as quickly as possible by composed driving, not idling.

Before we conclude this discussion, do yourself a favour and read the article written about “fake news and car care”. In that article, we discussed the issue of idling your car before driving off. We highlighted the reason why you should always idle your turbo driven vehicle. Read more about that here.

The Unichip

In the interest of a fail-safe approach, car manufacturers often opt for over-rich mixtures. This is especially the case when warming up your vehicle, or at full-throttle settings when at working temperature. How does the Unichip contribute, if any, to this entire process? When we fit the Unichip, it finely controls the mixture strength and avoid these scenarios. With the Unichip you actually stand to save fuel without having to modify your car at all. Practice responsible car care. Become part of the Unichip family and buy your Unichip today. Click here to contact us.




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