Effect of oil viscosity on mpg.
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You are still paying main agent prices to service your 11 year old car? That is a serious waste of money.0
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If it really was that easy wouldn't all the manufacturers being doing that? Might have saved VW a bit of reputational damage if they'd actually reduced emissions!Sure it will make a small improvement but I would suggest OP is exaggerating the benefit just like these miraculous claims of improved mpg, oil companies make for premium grade fuel.Remember the saying: if it looks too good to be true it almost certainly is.0 -
Changing from 5W30 to 0W20 will obviously reduce friction, that is a no brainer. However, I also find it very hard to believe it would make 8% difference to fuel consumption.
8% does seem quite high but people often don't realise how much of the energy in a tank of fuel is wasted inside the engine compared to what's used to drive the wheels.
In typical town driving something like 2/3 of every litre is used JUST to keep the engine running and less than a coke can's worth goes to actually turning the wheels / moving the car. So increases in engine efficiency do have an apparently disproportionate effect on fuel consumption.0 -
Maybe they checked the tyre pressures and put some extra air in?Censorship Reigns Supreme in Troll City...0
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Oh dear, yes I took the Honda to the main dealer! I do that every 3 years or so mainly so that I can borrow a courtesy car for the day and see whether the latest Jazz is any improvement on mine. The verdict so far has been negative. That's called "spend to save" (it costs me £10 for insurance but saves many £k on trading up). Other years I use a local garage which, in fact, isn't noticeably cheaper but is 2 miles away as opposed to 20.Strider590 wrote: »I give everyone a chance to prove they're not an idiot, I think that's a fair way to do things...... I can't help it if a lot of people blow that chance.
That said I never specifically called you an idiot, i was merely pointing out that throwing academics around is entirely meaningless.
When you come on here claiming that lower viscosity engine oil gave you miraculously better MPG, your lying to not only yourself, but to other people AND to make it worse your recommending something that could damage their vehicles.
I mean it sounds like you went to a main dealer (agents?), nobody who knows cars would do that, you'd be lucky if they'd even changed your oil at all, let alone actually driven it into the service bay. They're underpaid trainee technicians, who have unrealistic work targets to meet and WILL take shortcuts.
It could even be they carried out a firmware mod on the ECU while it was there and altered the cars ignition timings, this happens A LOT at main dealers, they covertly fix issues that the manufacturer has identified so that these issues never become public recalls.
Whatever the reason, it's not the oil. You don't know the specified pressure or flow rate for that engines oil galleries and as I explained, the wrong oil can and often does cause premature engine wear. The manufacturer has spent millions of £ on teams of very highly qualified and experienced engineers, determining the correct engine oil for that vehicle.
The engine in my kitcar runs 20w50 racing spec mineral oil, before I had the engine rebuilt, it ran 0w30 fully synth. The man that rebuilt my engine was an ex British Leyland engine designer, motorsport engineer and co-founder of Aldon Automotive, when he spoke, I listened.
Even worse, my xj8 goes to the main Jag. dealer once a year and has done so for 14 years now so they can't be treating it that badly as it's still running well. Costs little more than the Honda ...l'm wondering if they give a discount for elderly Jags. as a PR gambit.
Regarding engine damage I belatedly looked in my Jazz manual and see that you can use anything from 0w20 up to 5w40 over the temperature range below -30 up to above 40C so no probs. with the thin oil. I assume that you would trust Honda design engineers as much as you would your ex BL man.
The car is still showing 57.5 mpg but, as I said initially, I'm waiting to see if it's true effect. I wouldn't have posted this info. if I hadn't found it surprising. Hoping to get useful solid info. from others but no luck so far. Maybe I should try a different forum..... .0 -
forgotmyname wrote: »Car runs better straight after a service (shock), but you have only done 200 mile so not really a proper test.
How does the friction compare between a 0 and a 5 oil?
Actually that should be a shock. If a service makes the car run better then that means it's not being serviced often enough. A service should maintain the cars performance and not really improve it because the performance shouldn't noticeably degrade between services.
To the OP over how many miles is the 53MPG average and have you done the same trips when you were getting 57MPG?. My car sometimes varies more than 4 MPG between tankfuls depending on the weather and the type of trips I am doing.0 -
I've had the car from new so 11 years and it's done just under 55,000 miles. I reset the fuel computer from time to time but not in any consistent manner but it normally reads between 52 and about 53.5 mpg. Since the service it has never dropped below 57.0 but that's only around 200 miles so far. I can't guarantee to do exactly the same journeys as in the past but I'm trying to drive in the same manner as usual. As long as the figure stays at or above 57.0 then I think that I'm onto something as it has never read that before more than momentarily.0
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Don't have anything to add to the fuel consumption debate, but in my 10 reg Jazz (1.4 manual) I have found that the computer is a bit over optimistic (usally shows 52-53 MPG). A brim to brim test showed about 50 MPG.
Still, very good and I am happy with it, so much so that I prefer to use the Jazz when available (it's wife's car) instead of my Merc C Class as it's better in town and with very light controls.0 -
Strider: The car was serviced in September 2015 and had covered just under 5000 miles since. As the air filter and plugs were changed then they were not touched in September 2016.
I appreciate that you're an all round expert but in this case your predictions are wrong. It happens also that apart from having a Cambridge PhD in physics I also spent some time in the Shell Thornton Research Labs. so I know about oils.
What on earth are you asking on here for then? :beer:forgotmyname wrote: »Maybe they checked the tyre pressures and put some extra air in?
Fair theory I was going to suggest.Life isn't about the number of breaths we take, but the moments that take our breath away. Like choking....0
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