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The report I did was on this matter exactly. We found that the main reason why fuel consumption is highest at cold start was because of high oil viscocity. If you look at this chart you see how viscocity decreases logarithmically with temperature, this means that if you double the oil temperature you wont half the viscocity, it will be much less.



At low temperature the oil is like glue holding the engine together and this results in really high internal friction. This is why the engine needs to be warmed uo quickly. The designers do this by making the map so that it runs rich at start-up. You might think whats the point if the fuel is going to be wasted but its worth injecting more fuel to warm it up quickly than running cold for ages.

Another factor is that fuel doesnt vaporise properly when cold and so you get a poor mixture. If you have a poor mixture you will obviously waste fuel and is another reason why the engine needs to warm up quickly. I think the reason why cars run advance at cold is to give this poorly mixed air and fuel more time to burn.

i see! So if we use thinner oil let's say 0-40 it would be more economical too.

It would appear so, as long as the oil still lubricates adequately at high and low temperatures.

Oh Jangz I just got 43.8mpg on a mix off motorway (60mph) and city driving. Not bad considering my car is in a dire need off a service. Just proves the way you drive has a massive effect on fuel economy (i drive like a granny most of the time) =P

Yeah man I need a service big time yo, and dude driving slow in a civic is not granny driving slow in a civic is gangsta LOL, driving slow in other cars is.... ahhh rrgaahhh iii jusstt canntt mention the wwoorrddzzz. LOL

Yeah generally speaking I drive chilled out also, but what I have recently done is when I am at around 40 mph I dump the clutch or go to neutral when its safe to do so and cost a good few streets and whenever I notice a slight down hill. The burn and coast technique really helps and also having an idea of when to ease of and coast to a red light helps cuz by the time you get there its green and you can keep driving. Kinda like the hare and tortoise story lol the tortoise is an undercover playa. Driving this way is kinda like a bicyclist you don't need to peddle all the time.

After turbo it should be nice for general driving as i want to really find out for myself if driving smart with a turbo could save the same amount of money but also giving you that power on demand when you want it. there is a 3 stage civic d15 who got 55+ mpg with 230bhp so it can be done, even if i get the same 40 -49mpg with a turbo i would be loving it so will have to wait and see.

Yes driving habits make a big difference in saving fuel. Also its nice to hear your seeing gains also again thanks for info about why fuel is lost when the engine is cold etc, engine oil is one of the things i was also thinking about.

Yeah man

I've always been of the opinion that rolling in 5th gear (or any high gear) was better than proper coasting because then the wheels turn the engine (and so no fuel is required) instead of the engine essentially running at idle. However I'm not sure if our older ECU's are clever enough to know to stop injecting fuel and if not, coasting would definitely be be better. In fact hypermilers always seem to do what you do soits probably best. I can tell you though, driving at slightly less than motorway speed gives a big boom to fuel economy. As I said before drag goes up with the square of velocity and at high speeds you waste so much fuel just pushing the car through the air. I always roll at 60mph unless I gotta be somewhere then I go all out ( ) at 70mph

mynameisowen wrote:Yeah man

I've always been of the opinion that rolling in 5th gear (or any high gear) was better than proper coasting because then the wheels turn the engine (and so no fuel is required) instead of the engine essentially running at idle.

+1
Is better to have gear at hills because it is more economical and safe as well, than rolling at neutral and idle

The ECU kills fuel entry indeed, below some setpoint (you feel this) it starts putting fuel in again, around 1500 or so, and around idle rpm it even picks up with the idle valve(s) (DUH).

But I drove very much fuel saving style last couple of years... sometimes my brakes did not wear at all. Since I got into fishy problems with the brakes I started to actually use the brakes a bit more and harder again so the disks stay shiny all the time. Especially my EJ1 rear disk brakes had more rust build up than I could brake away. After two months of more braking style they are finally blank again.

So my point, don't go overboard with the fuel saving, especially in a country as the Netherlands were a slope of 3% is considered a mountain climb (its frikkin flat everywhere!), I actually could drive to work and back without a single time hitting the brakes if I timed everything right and only braked on engine.

Thats pretty awesome that you can manage that.

I use engine braking every time I need to slow down, once I get close to the stopping point I put the clutch down and use the brakes, so they still see some use.

Oh and thanks, I've always wondered what that little rumble was around 1500rpm when coasting in a high gear, now I know!!!

Yeah I agree you gotta know when to use the style. I have a set route to work and to the supermarket plus I know my area very well and the UK will throw all the hills, big ups and downs and very shitty roads but I got the hang of this style so I'm pretty chilling most time.

Also massively agree driving at 60mph compared to 70mph is like a 20% saving in fuel costs. Plus its only a matter of a couple minutes delay to any destination and its nothing big at all, so no need to kill myself, nor kill my pocket or fuel in my tank.

If I see a little incline/hill i will drive 40mph and then coast with that speed up or a little more, which then decreases the speed quite quick going up down to 30mph on the downhill and also pics up speed and manage to travel a fair distance after that LOL I will try and meet the next lights with at least 20mph.

Also just for the record, when I drive I am not the type to piss other drivers off, as I said its driving slow with style and when I need to foot it I will. Mind you, I noticed a lot of people driving to my speed so it seems a lot of people are slowing down these days. Except for morning driving LOL everyones car is timed in advanced LOL