Myth or Fact: Do you need to let your car warm up first before you drive it?
This is probably one of the earliest car-related myths you’ve ever known about, but depending on when you heard it, this might have been common practice which was actually recommended for the healthy upkeep of your engine.
Warming up your car would usually involve starting up the engine and leaving it running for a certain period of time before actually putting it in gear and starting to drive. On a purely logical basis, this makes perfect sense.
If likened to our own bodies, which needs to be ‘warmed up’ and/or stretched before a run or performing strenuous activities, why wouldn’t our engines benefit from something similar? After all, the engine, like our hearts, need to be primed and pumping at their peak to perform best.
First of all, we’re assuming that you’re reading this in Malaysia, in which case you’ll know just how unforgivingly warm and humid our climate can be, as well as how temperamental our weather patterns are. Our cars, even sitting at room temperature on any given day, are considered fairly warm by most standards in more temperate countries.
Paved With Good Intentions
Even in countries with legitimately cold weather, even in the grip of winter, leaving your car in an extended idling period upon start up has little to no benefit in prolonging the life of an engine. If the purpose here is to get the powertrain up to operating temperature as quickly and safely as possible, merely driving is the best way to do that.
In extremely low temperature conditions, contrary to traditional wisdom, it could be even more detrimental to your engine if left to idle from start as the low oil temperature will struggle to gain heat and therefore not exhibit its normal flow characteristics, stripping oil away from vital parts and possibly even starving the engine of lubrication.
The main reason why any advantage to warming up your engine is negated in modern cars is that current internal combustion engines have long eschewed carburetors in favour of fuel injection, helped by a multitude of sensors and computers to accurately and responsively alter the air to fuel ratio for optimal combustion, replacing the manually deployable ‘choke’ valve to temporarily restrict air intake and 'force' a richer mixture.
Therefore, during cold starts in a modern car, with the main aim being to get the engine internals and fluids up to operating temperature at an accelerated pace, the ECU instructs the fuel system to run a richer mixture of petrol/diesel to air (basically just upping the concentration of fuel). You may have noticed a higher idling RPM as a result.
It’s Getting Hot In Here
However, in addition to increased fuel consumption, this surplus of fuel being burnt also generates more heat, which needs flowing air to efficiently dissipate through the radiator’s heat exchangers. This is a problem if you’re not moving.
Basically, driving your car is the fastest way to get the engine warm so that the ECU can revert to its normal (more efficient) air/fuel ratio, but this doesn’t mean it's an excuse to drive your car hard just after pulling out of your driveway. This will only put avoidable strain and considerable wear on your engine, so try your best to have a chill drive until your car is nice and warm.
Some cars, usually the more expensive and higher performance ones, are even getting a little too clever in an annoying way, cheekily enforcing an electronic limit on how many RPMs you can access until it deems the engine ready.
The Real Killer
Everyone who has left their car 'warming up' by idling at startup when it was doing more harm than good has probably done so with good intent: to keep their cars happy and healthy for longer. Hopefully with this little explainer, they’ll see the error in their ways.
That being said, there’s really no avoiding the real enemy to longevity of our engines: idling itself. This is the villain. The big bad. The final boss battle.
Sitting still with no movement while your car is still running (a.k.a idling) is the single most inefficient and unhealthy thing you could be doing to your engine under normal conditions. Heat is continually being generated without any flowing air from the environment to cool and disperse it. Imagine being forced to do jumping jacks in a sauna. Not too comfortable is it?
Unfortunately, some idling is unavoidable since traffic is part of most of our daily lives. The engine is running, burning fuel, generating heat that leaves our poor radiator all but overwhelmed, and yet you’re not moving an inch. Worse, the cars around you, all bunched together, are doing the same thing, and expelling hot gasses from their exhausts.
Newer technologies like automatic start-stop literally circumvent this by turning your engine off temporarily, which is a rather blunt solution, leaving the electronics and auxiliary systems to rely on an onboard battery instead of a parasitic alternator. Still, the best remedy here is to avoid situations where your car will be left to idle as much as possible by planning your journey ahead of time.
With the intention of warming the engine, leaving your car idling after starting it up is analogous to being deliberately stuck in a traffic jam, an experience that’s universally disliked every motorist out there, but most of all by your car, so stop doing it. It is totally unnecessary.