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Thread ID: 125337	2012-06-21 05:48:00	91 Octane below $2 officially	coldfront (15814)	PC World Chat

Post ID	Timestamp	Content	User
1283212	2012-06-21 20:15:00	Basic article on which fuel to use here; www.caradvice.com.au Short excerpt Here’s the thing: you can put a higher octane fuel in a car than the manufacturer’s requirement. No problem with putting 95 or even 98 in a car designed for 91 – except generally you will be wasting money. Higher octane fuels don’t contain more energy. Octane rating is basically resistance to burning under pressure, allowing higher compression ratios to be used (cylinder pressures, actually). A modern engine designed for 91 will even deliver a very small amount of additional power if fed 95 or 98 because it will advance the timing a little more than with 91. The improvement will be very minor. So minor you probably won’t notice it Most engine design experts I’ve ever spoken to regard running higher octane fuel in an engine designed for a lower octane fuel as basically a waste of money. However, it’s an unmitigated disaster to put a lower-octane fuel in an engine than the one recommended by the manufacturer. This can lead to severe engine damage. The early detonation of the fuel can raise the temperature inside the combustion chamber to levels that the metal parts inside the engine can’t withstand, and unacceptable stresses are also placed on internal components. There are more detailed explanations available if you search around for anyone who's interested. I run my V6 camry on 91 because that's what it's designed for, 95 makes no noticeable difference for me.	dugimodo (138)
1283213	2012-06-21 21:27:00	Prtetty good explanation of what I knew already. Having gone through 2 major changes of fuel types in this country and in the UK, plus also working for BP Research in the UK. I guess I had a bit more knowledge on the subject than most. From my only experiance most engines in the UK were manually retarded to run on the lower octane 95 octane. Something the more modern engine management systems do autoomatically however the performance impact is not noticeable due to the high end speed impect effect thats not going to worry the average motorist. For my own vehicle type reducing the timing by a degree or so enabled it to run on a lower octane fuel 97 leaded to 95 Unleaded. VSR was not an issue due to the hardened valve seats however thats as low as this engine type will allow. The impact of this was the Top end maximum speed was reduced by a whooping 10 mph! But then I did not really need this is as 100mph fast enough :)	coldfront (15814)
1283214	2012-06-21 22:23:00	I have a JAP import with a Nissan VQ25DD engine in it. As far as I can tell from reading web sites, it has a compression ratio of 11:1 and therefore should be using 98 octane fuel. When I got it is was pinking quiote a bit, and it had 91 in it (from the dealer). I have run a few tanks of 98 through it (work pays!) and it 'seems' a lot better. I have no empirical proof, but it does feel and sound better to me.	trig42 (11325)
1283215	2012-06-21 23:14:00	Damn!!! I filled my car a few days ago before the price dropped. Ditto :angry but it only cost $125 to fill this time, last month it was $140	Gobe1 (6290)
1283216	2012-06-21 23:57:00	I have a JAP import with a Nissan VQ25DD engine in it. As far as I can tell from reading web sites, it has a compression ratio of 11:1 and therefore should be using 98 octane fuel. When I got it is was pinking quiote a bit, and it had 91 in it (from the dealer). I have run a few tanks of 98 through it (work pays!) and it 'seems' a lot better. I have no empirical proof, but it does feel and sound better to me. One of my vehicles is a 98 Maxima which I have owned for 12 years,this is the second one I have owned and years ago Nissan NZ sent Maxima owners a notification that contrary to what the manual said they are to be run on 95 Octane A lot of jap imports have different requirements and a lot of damage due to detonation can be done if not using the right fuel	Lawrence (2987)
1283217	2012-06-22 00:59:00	Japan uses 100 Octane fuel doesn't it? Follows that is a car is a Jap Import, it will be tuned for higher octane fuel? Sorry, bit OT.	trig42 (11325)
1283218	2012-06-22 02:26:00	Some points on fuel. 91 has more energy per litre than higher octanes because it has a smaller percentage of chemicals & a larger percentage of fuel. Most modern cars have octane sensors which adjust the settings to suit the fuel. If the compression ratio is very high you would probably have to use a higher octane. If its running well and not pinking use 91. 91 is less harmful to pipes and seals than the higher octanes. Valve wear due to unleaded fuel is a myth. What used to happen with leaded fuel was that a deposit built up on the seats and the tappets would adjust to this. If the fuel was changed to unleaded without a valve grind first, the deposit would come off and there would be no valve clearance - result burned valves. The lead was not added to fuel to lubricate valves, but to raise the octane rating. I ran a Holden V8 with cast iron valve seats for 150,000 miles on CNG (no lubrication) and had no valve trouble. I also ran a Nissan 280Z with a 260Z cylinder head, 11 to 1 compression ratio on 91 with a "Fuel Star" unit. It would not run on Super because the viscosity was higher and the jets were fixed.	mzee (3324)
1283219	2012-06-22 02:48:00	Talking about unleaded versus leaded fuel. In the mid 90s when we changed from leaded to unleaded fuels I noticed after the change I wasn't changeing mufflers so often. I had a 1600 Corolla at the time and one muffler only lasted 18 months, after the change I don't think I replaced a muffler again. In my 95 Honda Civic which I have had since 2004 it is still on its original muffler. :)	Trev (427)
1283220	2012-06-22 03:55:00	Tetraethyllead (common name tetraethyl lead) is very corrosive to exhaust systems.	mzee (3324)
1283221	2012-06-22 08:24:00	Talking about unleaded versus leaded fuel. In the mid 90s when we changed from leaded to unleaded fuels I noticed after the change I wasn't changeing mufflers so often. I had a 1600 Corolla at the time and one muffler only lasted 18 months, after the change I don't think I replaced a muffler again. In my 95 Honda Civic which I have had since 2004 it is still on its original muffler. :) I was drafted over here during the 1996 change over of Leaded to Unleaded and heavily involved with issues that came up in spectacular style in March of that year. Lot of myths misinformation etc came up during that period. Also about the same time the technology and metalurgy of Exhaust systems was improving. Over in Europe we were still adding lead in the fuel until 2000 your Honda Civic may have a stainless steel muffler meaning it will outlive the car.	coldfront (15814)
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