mandymoochops

I live in central AB. it can get cold here. Some days its been -38 (not often - but also the days surrounding those temps are cold).

I had an old Pontiac Sunbird / fire can't remember, anyway the red rocket was old but would start every day. Until one day when i'd had it sat around for a couple of weeks as hubby was home, so we would use his truck instead - and she died a death. She didn't have a block heater bless her.

So for a gas car - i'd say you probably wouldn't need one of it had regular runs, but if at least you were going to have it sit for prolonged periods, whilst not environmentally friendly, start it up and let it run for a half hour.

The diesel truck has a block heater and when temps get to around minus 15, hubby plugs it in every night. A lurching diesel engine is not a nice sound when you need to get to town and there's 2ft of snow in the driveway

Auld Yin

If you use winter quality oil and have a decent battery you should have little trouble starting an engine in winter in most of Canada.

ppc25

just to throw my 2 cents in all my cars and trucks i have owned have had block heaters. my diesel pick up i would plug in at -5 or below for the simple reason when using 15w-40 oil it starts to get pretty thick below freezing point and most people that haul stuff with there trucks dont use synthetic oil. It saves a huge amount of wear and tear on the starter and internal engine parts as warm free flowing oil will be pumped around your engine internals much quicker thus preventing damage. As for gasoline engines anything past -15 outside all day and i plug it in, also i recomend a battery warmer blanket which also has a lead in that you can plug in, this will stop your cells in your battery from freezing and is well woth the investment
If you got it use it

iaink

The theory is two fold.

1. Cold oil doesn't flow well, so on start up you (might) get metal on metal contact till it warms sufficiently to pump around all the nooks and crannies. This extra wear will eventually start to affect components, and eventually things will wear out sooner. How much sooner? Im thinking long after the body work has rusted away.

2. Cold thick oil and metal to metal contact = more friction. More friction means more load on the starter to get it going. More load on the starter means more drain on the battery, and its already struggling because its cold and that means the chances of failing to start the car go up. A battery warmer, which some vehicles in really cold places often have, would be as effective in that respect I guess.


In short, a newer car with a battery that is still in decent shape probably wont have a problem.

MikeUK

Nope, real simple, same every year, the debate on here is about which of two camps is right; one is general public opinion, and the other advice given by the government and automotive web pages.

iaink

Yes, vested interests never have any influence on governments.


Two things bug me about the official info.

First, they never talk about how much fuel you save vs how much energy goes into the block heater in the first place to pre warm the engine, so whether its a net gain or not isnt clear to me. I suspect with modern fuel management systems its a lot less clear cut than it was in the days of carbs/ chokes.

Second they are never specific about how much wear and what impact that might have on the life of the vehicle. Engines wear anyway, how much impact will a minute or less of cold oil actually have, expecially if Im trading in for a new vehicle every few years anyway.

There is also no clear indication at what temperature you should start to plug in if you are going too, which makes me think no one is actually sure. Kind of like the snow tire advice that snows grip better below 7C, that doesnt also point out that tires heat up while you are driving anyway...

MikeUK

As an engineer
Does warm engine run more efficiently than a cold one?
Does cold thick oil make an engine burn more fuel?
Does a cold engine partly combust fuel (you can smell it?)
Does unburnt fuel contaminate a catalytic converter and shorten its life, as well as pollute?
Does putting excessive loads on a cold battery shorten it life?

I know vested interests can influence government bodies and departments, and maybe it can influence the automotive reporters, but I’ve yet to see the lobby group change the rules of thermodynamics.
If you don’t like the official info, Take about 5 mins out from moderating and work out the numbers: The fuel $$$ v’s electricity $$$ can easily be worked out by comparing available energy in Kwh/$, with the high tax on fuel it can’t compete with electricity even it its was 100% efficient which it’s not..
electricty would be 600watts? for 2hrs, take local elec cost and compare that with the current cost of gas to get about 1.2kwh of energy, you mightprefer to convert to BTU's

The rest are so variable; yes, you can put numbers to it, but you know they would only apply on a case by case basis and attempting to create some all user average would make a mockery of the numbers anyway. Common sense should suffice for anyone with even a basic understand of a combustion engine.. granted I attempt to keep my cars running for around 10+ years so I want to keep it all running for as long as possible, and running as well as the day I bought it or better.

iaink

Of course it does all those things, although part of the problem is quantifying how much extra wear and tear really occurs, and whether that would have any impact on vehicle life expectancy in a nation where rust tends to shorten the useful life of a vehicle anyway.

Do you have figures for how much extra fuel running a cold engine uses, and for how long? Ive found that hard to pin down. My point is simply that on the other side of the scale the block heater is drawing power from the grid for a couple of hours, and that has an environmental cost associated with it too.

MikeUK

yep.. posted the link to cold engine fuel consumption in my first post #15 second link


All my calculations and data sources would show that the theoretical upper energy recovery from 100% combustion of gas/petrol (absolute max) is 33.6kwh /l

In a an internal combustion engine you’re not going to get close to that figure, as its theoretical upper limit of efficiency is 37% and a more realistic efficiency value would be 15 to 20%, even if we assume all those losses end up as heat, a significant amount of that is going out the exhaust. Lets assume we get 30% of the theoretical upper limit heating the block (IMHO f*ing optimistic).


a block heater converts at 100% efficiency as its pure resistive heating

So at Ontario’s worst hourly rate we’ll get 10.4C per Kwh the lower off peak rate is when you more likely to use a block heater at 5.9c/Kwh

So for $1.25 of gas with 33.6kwh at 30% we get 11c per kwh and that’s under very optimistic conditions as the engines cold we wouldn't even get close to the 33.6kwh

The block will absorb the energy to heat up, it’s a choice how you choose to pay to heat it, and as far as I'm aware overall commercially generated electricity has a lower greenhouse/emissions/pollution impact than a gasoline powered car

expatdoris

Oh, I suppose we will end up getting a car with one then! Thanks.