$/100km. 91 v 95 octane petrol?

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Gordy7

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#113981 3-Feb-2013 21:13

I am looking at getting a small car to get to and from work.

Some run on 95 and others 91 octane petrol.

One car is rated at 4.8ltr/100km using 95.
Another car 5.5ltr/100km using 91.

With the different prices of fuel how can you make an effective comparison?
Is the pricing of 91 and 95 based on the the amount of energy that can be extracted?
No doubt there are manufacturing, usage and tax issues.

Cheers

Gordy

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#755226 3-Feb-2013 21:20

Cars are tuned for specific octane fuel - you won't necessarily get any better performance with the different octane. Try running 91 in an engine tuned for 95 and you will notice sluggish performance..

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nakedmolerat

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#755229 3-Feb-2013 21:30

I personally will pick a newer japanese car - cheaper maintenance overall (remember, there are other additional costs apart from petrol).

rayonline

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#755234 3-Feb-2013 21:40

Just branching on something I am curious about and may be of usefulness to the OP. Those of you who have cars, how much regular maintenance do you do on it? We always change the oil and filter every 6 months, the Hays car manual from the library says least once per 12 months but they also prescribe items like air filters, fuel filters, spark plugs, flush the radiator and brakes. We obviously change the various belts after a certain time. But yeah ... how much of the maintenance jobs do you do to the car? I cannot remember the if ever we changed the spark plugs, fuel filters, air filters unless the mechanic picked it up. But we had 5 or 10yr old cars that were in tidy condition .....

tardtasticx

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#755237 3-Feb-2013 21:48

I've never used a 95 octane car but 91 seems to do just the trick I guess. 2001 nissan Primera has a 50/60L tank, and goes about 600-800KM on that depending how I drive it. Driving to Takapuna every day usually lasts me about 800KM. Its not the most efficient car but better than parents cars that us 95.

For the servicing, not quite sure, I just give dad the keys every 6 months, he takes it to the shop where he knows the guy, gets everything checked and warranted etc and I pay him back for whatever needed doing. Easier and I know he knows what he's doing lol. Dont jump on me about this, I've changed my wheel before on the side of the Auckland Southern Motorway near the CBD, so I'm not worried about minor tasks like that, and checking oil and obviously doing gas etc. :P more than mum can do. But I've never heard of them replacing my spark plugs, how would I know they need to be replaced?

richms

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#755243 3-Feb-2013 22:05

I took my car in for idling rough and they changed the sparkplugs to sort it. I think they can pick it up on the diagnostics too since something more modern will increase the idle to stop it being rough and then log that for when it is service time.

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rayonline

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#755252 3-Feb-2013 22:11

tardtasticx: But I've never heard of them replacing my spark plugs, how would I know they need to be replaced?

Yeah .. if there was nothing wrong our mechanic does nothing and our sparkplugs afaik have not been replaced maybe once that's all when it had issues. The Hays manual at least puts items on a schedule even when no probelms are noticed. Ie, every year or 6 months the general WOF stuff like hoses, belt inspection, oils, other liquids top up. But it also prescibes every 4yr or 40,000Miles (whichever earlier) or something like that ... and it says flush the radiator and brakes and change the sparks ....... They may had a 20,000Mile cycle as well for the air filters ... from memory.

Yeah .. every 2 or so years, sparks are pulled out, inspected, cleaned and the pin thingy is adjusted to the right height and put back in and lubricated. Every 6 months or so the battery contacts are inspected and cleaned.

D1023319

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#755254 3-Feb-2013 22:20

rayonline: Just branching on something I am curious about and may be of usefulness to the OP. Those of you who have cars, how much regular maintenance do you do on it? We always change the oil and filter every 6 months, the Hays car manual from the library says least once per 12 months but they also prescribe items like air filters, fuel filters, spark plugs, flush the radiator and brakes. We obviously change the various belts after a certain time. But yeah ... how much of the maintenance jobs do you do to the car? I cannot remember the if ever we changed the spark plugs, fuel filters, air filters unless the mechanic picked it up. But we had 5 or 10yr old cars that were in tidy condition .....

good points you raise with brake pads and battery water levels a obvious omission

As a non mechanic - this is what I do but depends also on car. FYI - my ute has more than 400k on odo and is still averaging 7l per 100km with no maintenance issues.

for diesel, you normally do more frequent oil changes at about 5k km and air filter has big impact on fuel efficiency. I own diesel ute but only replace air filter every 10k as i drive on clean city roads - on dirty roads you need to change more frequently.

I also had a oil test at 5k a few years ago - this told me state of engine, engine wear and soot levels and the test recommended oil change every 7.5k which meant savings

petrol cars, every 10k for oil change is ok and once a year for air filters.

fuel filter I dont think need to be changed that often - depends on turn over of fuel at your local station and dont let your tank get too empty.

Not too many nipple joints for grease on modern vehicles eh from memory universal, and a couple of steering ones.

only flush radiator every 5 years but always check has green stuff in it to combat rust and metal reactions - rather than cooling.

rayonline

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#755265 3-Feb-2013 22:43

Thankis! But .. obviously a non mechanic would not touch much of that. How essential is it? The oil yes, others to be left to mechanic? I can do a bit .. myself and like to do it myself when I can but how essential are they?

D1023319

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#755273 3-Feb-2013 22:54

rayonline: Thankis! But .. obviously a non mechanic would not touch much of that. How essential is it? The oil yes, others to be left to mechanic? I can do a bit .. myself and like to do it myself when I can but how essential are they?

as I said - I am non mechanic and its easy.

look at air filter - if dirty replace as it really affects your fuel economy.

if nothing else - take the caps off your car battery and look inside. if the "water" level doesnt cover the plates - top up pref with distilled water.

rayonline

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#755274 3-Feb-2013 22:58

thanks again :) think we might have a low maintenance battery, the thing is just to get to the battery we have to undo many covers it's next to the firewall (close to the dash) unlike the camry ... might get around to the air filter soon. they never changed that ever in the last 15yrs! nor the air element.

nakedmolerat

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#755281 3-Feb-2013 23:19

rayonline: Those of you who have cars, how much regular maintenance do you do on it?

I just follow whatever it is in the service book... I mean I send the car to dealers, they just do the service whatever required.

Disrespective

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#755341 4-Feb-2013 08:41

Our new car uses 95/98 and it's more thirsty than I had thought around town. On the open road it gets us about 6.5L/100km and it's a 2.4L Turbo. I don't know what our old 91 car did sorry.

We do services every time the car needs a warrant. So that was 6 months for the old car, as it was old. And 12 months for the new car, as it's new.

Every month or so I check the water, oil and filters. I have an OBD2 bluetooth adapter so I can diagnose anything more serious that pops up on the dash with my phone.

rayonline

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#755348 4-Feb-2013 08:51

To the OP my guess would be that take the market price of 91 and 95 fuel today and do a calculation for those rates. Most cars incl rentals thta I have come across just ask for 91. A normal car that takes 91 might see a bit better mileage with 95 but not sure if the prem. price makes up for it. You could just get a Haynes manual out from the library and check with it recommends.

If it is just a commuting car, maybe look at a more compact car. That is if you don't really do open road driving much. It would be more efficient, also things like tyres would be cheaper too. I've just been looking at the tyres, and reading consumer mag. It seems that unless it's the top model Firestone, all the tyres Joe or Jane goes into a large franchise in NZ may be just be buying budget tyres. All the consumer mag tyres are decent quality, many of them are european imports. Joe or Jane goes into a large franchise and get some price quotes right ... the guy gives a few prices the bottom and the middle option IME has been budget tyres. The top option is maybe decent but they just exclude performance tyres to the average motorist maybe, at least on the phone. I see that the medium size cars may be a $50 prem. over small car tyres for the same brand/model.

Goosey

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#755355 4-Feb-2013 09:03

Depending on the city your in, the quoted fuel eff figures just wont match i.e. the fuel eff figures are complied by driving a 100km distance at a constant speed and NOT normal around town / traffic driving.

Agree with others... regulary change your oil, oil filter, air filter, air cabin filter, water in radiator and tyre pressures !

I fond I get more km's from higher octane (car designed for high octane) and you have to be careful using lower octane as many will know their cars 'ping/clatter' when you put the foot down which isnt good at all for the car.

Dairyxox

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#755360 4-Feb-2013 09:19

Another thing to consider is the availability of 95 octane fuel.

I have a car which is supposed to run on 95 but it is impossible to purchase in my area (I live in Tauranga). Most service stations here sell 91 & 98. So you pay a premium to keep your 95 car healthy.

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