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Wheels/Tyres / Re: what tyres?
« Last post by moozmooz on Today at 12:49:20 AM »
The last time I had tyres fitted on my Gen 1, the fitters spent ages grinding off the corrosion and crud from the wheels before fitting the new tyres with a heavier than normal sealant compound. They reckoned this was fairly common on alloys that age, so maybe your tyre fitters weren't so enthusiastic.
Mazda 3 / Re: The Mazda 3 Fuel Economy Thread
« Last post by moozmooz on Today at 12:43:36 AM »
Difficult to find corners in underground fuel tanks as they're normally cylindrical cross section with domed ends, so I'd take that theory with a huge pinch of salt.

The temperature/volume idea's also a bit of a non starter. If you look at the volumetric thermal coefficient of expansion for petrol, it's tiny, so you're not going to see any meaningful change across the normal operating temperature range. So the density won't vary much meaning that the mass of fuel you're buying, and therefore the amount of energy you're buying, is as near as damn it constant.

Interestingly, petrol and diesel are about the only fuels I can think of where you're buying blind, as there's no indication of the energy content or calorific value, and the fuel companies aren't keen to tell you either. They'll only quote you over a fairly wide range.

This is one of the things that raises huge doubts about the mileage benefits claimed by some, but, interestingly, not the fuel companies. To get more miles out, you'd need to be putting more energy in - ie higher CV. The only apparent difference is the additive package.
Wheels/Tyres / Re: what tyres?
« Last post by StevenRB45 on Yesterday at 11:45:51 PM »
Iirc disc diameter is the same on all 1.6s. As long as you go up in side wall when reducing the rim size rolling diameter is the same. Think you'd find your space saver is a 15 inch wheel. It may be classified as a mod on your insurance though.

Not heard of prestivo but having had landsail..I'd avoid anything I've not heard of like the plague.
Mazda 3 / Re: The Mazda 3 Fuel Economy Thread
« Last post by StevenRB45 on Yesterday at 11:41:43 PM »
I'd read it was a simple as pumps measure volume not quantity as such. Hot fuel = more volume and less for your money, cold fuel more dense and more for your money.

However it's a going beyond the far end of a fart to test that for me... ;)
Wheels/Tyres / Re: what tyres?
« Last post by Engineer Andy on Yesterday at 06:36:15 PM »
Hi all just wondering if anyone has had experienced Prestivo tyres on there car

Sorry mate - never heard of them, though you might want to do a Google search on them first.

On an unrelated issue - has anyone ever thought of going down a wheel and tyre size on their car (obviously not those with 'Sport' or MPS models, which can't due to the bigger brakes).  I ask as my Mazda3 mk1 1.6 petrol TS2 has 205/55 R16 V tyres, and I'm starting to think about changing the tyres again, even though the current Dunlop SP Sport FastSesponse ones are doing ok (4-4.5mm on the fronts, about 5-5.5mm on the rears), they are now nearly 6 years old and may soon get quite hard, as the previous set of awful Bridgestone ER30s did (but at a much earlier stage), leading to very bad wet grip and a noisy ride.

Given my car is essentially the same as the TS model with 195/65 R15 H tyres (same engine and, I think, brakes), would it be possible to 'downsize' legally, so that my insurers would accept them all year round, and not just winter tyres as some do.  I would prefer the extra cushioning effect of the higher profile tyres, which was noticeable when I drove a 1.6p TS which was a work pool car some years ago, and there seemed to be little difference in grip.  To me, this would be handy, as my 16in alloy wheels have corroded a bit and must of deformed slightly as well, as it took two goes and a decent amount of sealant to stop one of the tyres from deflating quite quickly when I had the tyres replaced last time.  I've noticed that I have to pump them up more often than I used to as well.  As such, it might seem prudent to replace the alloys at the same time as the tyres, but Mazda charge £154 each for ths closest design to my 16in OEMs (a nice 16in alternative costs £104), but the 15in version only costs £88, a huge chunk of money less for four.
Mazda 3 / Re: The Mazda 3 Fuel Economy Thread
« Last post by Engineer Andy on Yesterday at 06:15:37 PM »
Well mysteriously the one tank of 95 I've ever run in this car is also the worst mpg I've ever got out of the car. So 36.8..I've never been below 37 (checked back through fuelly) in 28k I've had the car.

Also the first time the trip computer has been optimistic as well, normally I get about .5 mpg better brim to brim than it says this time it was .5 worse than it said.

Yes winter will be having an effect..but it's 3 years of data including 3 winters.

That seems about right and agrees with what I've found my 1.6p can get on 95RON in cold, bad weather and heavy traffic to work (35.5 - 36mpg at about this time last year going to work - worst conditions in all respects I've come across [mine normally does an average of 37mpg in the dead of winter).  On superunleaded, mine's currently averaging about 38.5mpg though not on quite so much traffic (similar weather).

I'm also wondering if it makes any difference which filling station and pump you choose, as well as the day/time, e.g. just after the tanker delivers the fuel, or the last drop-off for them, plus the pump that takes from a corner of the underground tanks....?

Whilst most filling stations are well used, so fuel doesn't sit around for ages like it can do in car tanks, I'm wondering if the big underground tanks suffer from poor mixing, especially in the corners, where old fuel may linger and thus give poorer performance if you take fuel from a pump that uses that area of the tank.  I know this is a problem with water tanks and is often the cause of bacteria growth if the inlet and outlet pipes are not on opposite sides as well as top and low level respectively.  Just a guess as regards fuels though.

I read once that you should buy fuel when the temperature is at its lowest as it expands with heat. So first thing in the morning when it has had time to cool all night is probably best. Conversely 9 or 10 pm is probably the worst time. Maybe there is some truth in this

I did read something similar that you should always buy petrol when its coldest outside, though more to do with less evaporating off the nozzle and fuel pipe as you actually fill it, as petrol can vapourise quite easily at daytime temperatures compare to colder nighttime temperatures.  I suspect that the density will vary in the underground tanks to a degree as well, though not as much as you think - the temperature of the ground is relatively constant throughout the year after going down over a meter or two, which is why ground source heat pump systems to provide heating to buildings often have their heat 'source' pipes at that depth.
Mazda 3 / Re: Boot won't opn
« Last post by StevenRB45 on Yesterday at 04:58:43 PM »
My first thought would be change the battery in the keyless fob, may be it's a too weak to communicate with the car.
Mazda 3 / Boot won't opn
« Last post by Gerry77 on Yesterday at 10:27:44 AM »
Hi needing some help/advise my Mazda 3 gen 2 2009 boot won't open. When I press the unlock button on tail gate the wee red light on keyfob won't flash Unlike when I press the button on the driver/passenger door it flashes. Help is much appreciated. Thanks
Diesel /DPF issues / Re: Strange odor inside the cabin
« Last post by amar1994 on March 22, 2018, 05:33:15 PM »
Screen wash?
thanks for reply

no , definitely not screen wash , more like fuel/coolant mixed smell
Diesel /DPF issues / Re: Strange odor inside the cabin
« Last post by moozmooz on March 22, 2018, 12:43:07 AM »
Screen wash?
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