General Question

cadetjoecool's avatar

How do you tell if a car's engine warms up faster by idling it, or just driving it?

Asked by cadetjoecool (218points) February 9th, 2011

I’ve read countless articles that just say “you should let older cars idle, but modern cars don’t need to”. How do I actually tell if a car is an “older car”. If it makes any difference, I have a 1997 Mercury Sable (the car one, not the wagon).

Observing members: 0 Composing members: 0

12 Answers

Axemusica's avatar

A cars engine naturally degrades of time and use. Using oil as a way of lubricating the massive friction produced by the constant motion of the pistons. Naturally an older engine will have more of a degrade than a newer one.

Also, you just really need to let the oil heat up rather than the engine temperature. The oil is much thicker and actually harm engine components when it’s cold. Also, oil pressure plays a factor in this too. If the oil is too thick (due to it being cold) it won’t be able to flow freely throughout the engine as intended and some parts of the engine could still be dry because of that fact. Realistically you should always let it run for at least a few minutes before operation, but that could just be me.

woodcutter's avatar

If you have ever started a car in winter and heard a loud tapping right away it’s because the engine is dry there. Not a good idea to put any more stress on those parts till there is sufficient lubrication throughout the engine. Usually there is window glass that needs defrosting or possibly some shovel work to remove some snow so if the engine has been idling for a few minutes while this is taking place it should be good to go. Because we all agree that the ice should be cleared from the glass all the way, side to side, top to bottom all four sides I hope.

meiosis's avatar

Idling for a minute or two in winter is definitely worth it. The handbook for my modern diesel says that journeys under ten miles from a cold start are considered the most damaging to the engine as it hasn’t had time to properly lubricate before the cooling process starts.

@woodcutter I’m afraid not everyone agrees with your sensible advice about clearing the windscreen. Don’t miss the world championship stupidity at the bottom of that link., btw

SABOTEUR's avatar

The answer seems simple enough.

Sit in your car while it’s idling. Time how long it takes for the temp gauge to reach half-way. (Or notice when the heater begins to blow warm air.)

The next time, start driving from a cold start and see how long it takes.

Compare the two times,,,there’s your answer.

mattbrowne's avatar

The determining factor is the consumption of energy, which, unless you can let your car roll down a hill, is higher when you are driving. Warming up is a result of waste heat.

marinelife's avatar

That counts as a newer car.

Meego's avatar

I think if you have a car from 97 that is considered older, there are also a lot of other factors like miles on the car how it has been driven, because 15 years is a long time think about it if you walked everyday all the miles your car has. But I would let the car idle for a few minutes at least just to be on the safe side I do this always, that also gives me a few moments to listen to see if there is any unfamiliar sounds as well, and I have had many different cars and sad to say the only car I had that caused me numerous amounts of problems was my very first car I ever owned which was a Mercury Topaz. Years later I went with my husband to test drive a brand new Ford Explorer Eddie Bauer Edition SUV they had just got it on the lot, half way through the test drive the check engine light came on! :/ I was not impressed and I vowed at that moment to never buy any Ford, Lincoln or Mercury product again. Our first SUV was a KIA Sorrento, best vehicle I ever owned…and it also saved my life when a van hit me head on at 70km I’m not sure what that is in miles.

achenier's avatar

The fastest way to bring an engine to ideal operating temperature is to put torque on it. This is done by immediately driving the car.

This is important because nearly all the wear on a car engine occurs during the first minute or so of starting when it is cold. You want to make that time as brief as possible.

If you can afford it, use synthetic oil. It gives full lubrication protection even when it is cold, so there is no metal to metal contact as is the case with conventional oil before it warms up.

Axemusica's avatar

@achenier Would I be bold to say that even synthetic’s are effected by cold? I mean, I’m no petroleum physicist, but I have poured some synthetic that has been in the cold for a while and it wasn’t exactly free flowing or as free flowing as, let’s say, room temp.

achenier's avatar

I am not a petroleum expert either, but I have done a lot of reading on the topic of engine lubrication. It seems undisputed that synthetic oil retains its viscosity much better than conventional oil in cold temperatures. It therefore reaches internal parts of the engine more quickly and prevents metal to metal contact that causes wear.

Synthetic oil would also prevent shearing under very hot operating conditions. Shearing is when the oil film protection breaks down and allows metal to metal contact.

My personal experience supports this. I keep my cars (GMs) for a long time and average well over 300 000 kms before I trade. I have never experienced engine wear symptoms with those cars. For instance, even at those high mileage levels, I never have had to add oil between oil changes. And the engines always retained their power and fuel efficiency.

The other advantage of synthetic oil is that they are not petroleum based, which makes them greener.

From what I have learned, conventional oils of today certainly offer adequate protection. Most people use them, and cars today outlast those of yesterday by a wide margin. I remember when an engine had reaches 100 000 miles, it was at its limit, and “ring jobs” where required.

But I still use synthetic oil because I simply like to have the impression (justified or not) that when I start the engine at 20 below, or drive for hours in hot temperatures, minimal damage occurs to the engine.

BTW, a person earlier reported that the temperature gauge rises more quickly when the car is not driven. I have not observed that, but if its true, it could be explained this way: the temperature gauge measures the temperature of the coolant, not of the internal parts of the engine. When a car moves the heat from the coolant is dispersed, giving the impression that the engine itself is colder.

Axemusica's avatar

lol no reason to explain yourself to me @achenier I couldn’t agree more. I just had noticed how hard it was to poor as it was oil that had been left outside. I also only use synthetic (when I do own a vehicle at that time), because I too understand the characteristics of how it’s engineered and what it’s supposed to prevent. I have yet to witness shearing though & I hope I never do. :) happy driving.

achenier's avatar

Glad you agree, and sorry I over-reacted…! But I do wonder why that synthetic oil of yours did not seem to flow more than conventional oil when cold. Maybe the difference is so small that it is not noticeable visually but significant enough to affect its performance inside the engine.

Answer this question




to answer.

This question is in the General Section. Responses must be helpful and on-topic.

Your answer will be saved while you login or join.

Have a question? Ask Fluther!

What do you know more about?
Knowledge Networking @ Fluther