Fuel Debate RON Vs RON!

[Ratbag]

Anything over 90 octane is perfectly fine. Here's the info direct from Subaru - https://www.subaru.com.au/service/maintenance/fuel?ref=mobile
If it pings, there's something wrong with it. Hope they get to the bottom of it for you.

I agree, Andrew.

Our 91 RON is the same as everyone else's 91 RON. Some other countries use different measures of the octane rating of petrol, but the outcome is the same when the same methodologies/measuring systems are used.

The bonnet sticker on my MY06 reads "90 RON". Ditto the Impreza and the Camry. Almost never used anything else. AFAICT, the supposed fuel efficiency gained from using higher octane rating fuel than is required is mostly in the mind of the teller of the tale ... I have kept dead accurate records for all our cars for well over 20 years, and the variation per tank (per litre ... ), is always attributable to the driving conditions during that tank. When I have had to use higher octane rating (or have experimented with it), there has been no difference in fuel use. Certainly not sufficient to justify the 5-10¢/litre price gouge!

Ditto as regards performance, smoothness, starting, etc, etc ...

We have only experienced any sort of problem from fuel twice:

1) when there was a contaminated fuel batch that left over 300 cars stranded all over western Victoria, our Impreza included, and

2) the recent CEL in our SH may have been partly attributable to some minor fuel contamination. The CEL was far more likely to have been caused by a battery that was all but completely shagged, however! In the absence of enduring CEL codes, we will never know.

 

[NachaLuva]

In a modern car a higher octane will produce higher power. More power with similar driving gives better economy. Something I have noticed with better power & better economy. However, it costs more per litre & per km

 

[Ratbag]

Gidday NL

In a modern car a higher octane will produce higher power. More power with similar driving gives better economy. Something I have noticed with better power & better economy. However, it costs more per litre & per km

In my distant youth, this was correct. I used to put a 1:10 racing fuel additive into my hot Morris 1100 ( methyl benzene - commonly known as "benzene" - aka toluene), along with the 100 octane leaded fuel available then. The engine was manually tuned to this fuel mixture.

Modern engines tune themselves and the algorithms used are optimised for the engine, and the fuel it was designed to run on. My EJ-253 is designed to run on fuel with an octane rating of 90 RON. It runs perfectly well on the 91 RON fuel available in Oz. So did my Impreza, and the Camry. None of the cars we owned before this used any kind of ECU.

Unless you keep precise records over a long period of time, there is simply no way to support your assertions. I have kept these records for 13 years for the Camry, and nearly 18 years for the Impreza. These records do not support the assertion that using a higher octane fuel (higher RON) is beneficial in any noticeable way. Sorry.

Using an ethanol mix fuel is highly risky according to Ross, for the reasons I have previously stated. There is simply no way to protect oneself against the risks he outlined, which is why Shell doesn't sell ethanol mix fuels anymore.

Anyway, whatever rocks your boat ... :biggrin:.

 

[NachaLuva]

Would detailed records from the day my Forester left the car yard over 15 years ago count

I can verify that using lightweight alloy wheels increases economy, so does higher octane fuel and muddies reduces economy. I can say these things beyond ANY shadow of doubt!

RB, think about the reasons. Modern cars with modern ECUs constantly adjust timing for maximum advance before pinging. The higher the octane, the more you can advance the timing. So not only are you getting more power from the fuel, you're getting more power from the timing. Double bonus! :biggrin:

At the same speed, more power equals more economy.

So higher octane means less fuel used to cover the same distance. Better economy!

Leaving this aside, Subarus are NOT designed to run on 91RON. Subarus are Japanese designed & built. regular fuel in Japan is 95RON so thats what its designed for. Just because in most cases the ECU can adjust for 91 doesnt mean all Subie engines will run properly on 91. The proof is all the people who complain of pinging on 91 & believe me, there's a lot! Not just Subaru either...

Remember we are giving advice to someone on their engine pinging...pre-detonation. This is what causes engines to destroy themselves! BOOM!!!

It might be better to err on the side of caution & recommend a higher octane don't you think? It can only help whereas advising 91RON may cause permanent engine damage. There is a reason why many people ONLY use premium on their Japanese cars, 95RON minimum.....

 

[Ratbag]

Would detailed records from the day my Forester left the car yard over 15 years ago count

I can verify that using lightweight alloy wheels increases economy, so does higher octane fuel and muddies reduces economy. I can say these things beyond ANY shadow of doubt!

That I will accept. AFAIK, you have never mentioned before that you have kept these records ... :iconwink:.

RB, think about the reasons. Modern cars with modern ECUs constantly adjust timing for maximum advance before pinging. The higher the octane, the more you can advance the timing. So not only are you getting more power from the fuel, you're getting more power from the timing. Double bonus! :biggrin:

At the same speed, more power equals more economy.

So higher octane means less fuel used to cover the same distance. Better economy!

I have not observed that with any of our cars that were designed to run on standard grade petrol. Certainly not the ones with ECUs - Camry, Impreza, series II SG and series I SH.

Leaving this aside, Subarus are NOT designed to run on 91RON. Subarus are Japanese designed & built. regular fuel in Japan is 95RON so thats what its designed for. Just because in most cases the ECU can adjust for 91 doesnt mean all Subie engines will run properly on 91. The proof is all the people who complain of pinging on 91 & believe me, there's a lot! Not just Subaru either...

Funny then:

Australian Supplementary OM for SG series II:

Relevant extract from the above:

Under bonnet sticker from series II SG:

Sorry about the photo quality, de Sun is very bright; de wind is blowing; I could not see what I was doin' ...

Remember we are giving advice to someone on their engine pinging...pre-detonation. This is what causes engines to destroy themselves! BOOM!!!

The only time I have ever experienced pinging in the Impreza was driving up the Cape Patton Hill heading east, with 4 adults on board in fifth at around 1,000 rpm ... Needless to say, I changed down a couple of gears!

It might be better to err on the side of caution & recommend a higher octane don't you think? It can only help whereas advising 91RON may cause permanent engine damage. There is a reason why many people ONLY use premium on their Japanese cars, 95RON minimum.....

There is a reason that most people use the recommended fuel for their cars. It is because this is what the manufacturer has designed the car to run on ...

As was said earlier in this thread, and I agree, if the OP's engine is pinging, he (that is, the Subaru dealer ... ) should find the cause and correct that cause. Otherwise there is a real risk of engine damage.

One possible cause of the pinging is the quality of the fuel being used. This can and will cause problems. I almost invariably buy from "proper" outlets who are using (hopefully ... ) fuel of a known quality from a single supplier. These servos are more likely to perform routine maintenance on their fuel storage tanks as well.

One of the questions Ross asked me about the recent problem with our SH was "Where do you buy your fuel?". When I replied "Caltex", he said that they would be OK. Not that I have ever had a problem traceable to fuel purchased from an independent servo, just that they are likely to buy from the cheapest supplier, and possibly less likely to perform that routine maintenance on their in-ground tanks.

 

[Ratbag]

As at 5 minutes ago, in our area of Melbourne, PULP95 is 9-11¢/L more expensive than ULP, and PULP98 is 14-18¢/L more than ULP.

It's not so much the quality of the fuel that's RS in Oz, it's the pricing ...

 

[guzzla]

Very interesting reading.... Now my 2c worth.
Standard Japanese petrol might be 95 RON but the engines they use there aren't the same as we use here.

It's rubbish that Japanese engine cars here should be running 95 RON when the manufacturers have specifically said they are suitable for 90-91 RON (like the N/A Subarus) I know plenty of people with Subarus who run 91 RON exclusively and have never had pinning problems. And no one has ever been able to demonstrate to me with believable evidence that they get better economy / performance.

I also have kept comprehensive and accurate records (although now thrown out with my Camry V6 352,000km), Forester 267,000km and now Golf 59,000km. You could say I'm OCD about it :lol: SWMBO certainly thinks so. I just call it being a bit fussy.....

With my last car, a Camry V6 manual, Toyota Australia claimed it made 141kW / 279Nm on 91 RON and 145kW / 284Nm on 95 RON. I would use it for months on end with one fuel type and then months on end with the other fuel type. This basically got rid of the mixed fuel factor. I could never tell any difference in power, performance, drivability and definitely not with economy. And I was convinced it should be there. For a number of years we were doing regular trips from Toowoomba to Newcastle via the New England H'way. I just knew after time that Camry would achieve 7.3L/100km on those trips with either fuel. It was so predictable that car. The few times I used E10 the consumption increased about .5L/100km but the performance didn't change.

My Forester XT is designed to run on 95 RON and that's what it got (before it got the reflashed tune) with occasional periods of 98 RON, just like I did with the Camry. It made no difference to power or fuel consumption. In fact the 3 times I was forced to use 91 RON (once each in Nanango, Thargomindah & Tibooburra) even that didn't make a difference and there certainly was no pinging. I admit that each of those times there would have been some 95 RON mixed with it because of the one off fill.

Differences between using 91 RON and 95 or 98 RON in Japanese cars designed for 91 RON could only be measured under tightly controlled conditions that we could never hope to be able to replicate on public roads. Wind, gradients, road surfaces, temperatures, traffic flow, weather conditions such as rain, tyre pressures, varying loads such as extra passengers or luggage will always make it impossible to be really consistent even with the same driver in the same car.

The above factors have really been brought home to me with our new Golf, which gets a regular 450km weekly trip from Toowoomba to Goondiwindi and return. It has a wonderfully sensitive fuel monitoring system that makes the displays I've seen in the latest Corollas, i30, Yaris and Impreza etc Japanese / Korean stuff look truly amateur. And I always check then with the "real" reading at refuel time. It has really made me aware of the sometimes subtle / and not so subtle differences the above factors make. I wasn't aware that driving in the rain increased consumption for example, but now I have the proof.

Short version: put 95 RON / 98 RON into a N/A Forester designed for 91 RON and you're wasting your money and delusional if you think it is faster / more economical.

 

[Davidov]

Very interesting reading.... Now my 2c worth.
Standard Japanese petrol might be 95 RON but the engines they use there aren't the same as we use here.

It's rubbish that Japanese engine cars here should be running 95 RON when the manufacturers have specifically said they are suitable for 90-91 RON (like the N/A Subarus) I know plenty of people with Subarus who run 91 RON exclusively and have never had pinning problems. And no one has ever been able to demonstrate to me with believable evidence that they get better economy / performance.

....

Short version: put 95 RON / 98 RON into a N/A Forester designed for 91 RON and you're wasting your money and delusional if you think it is faster / more economical.

Not to start an argument or anything but I think its delusional to tell people whether their experiences are delusional based on your own opinion don't you think.
I know for a fact higher octane made a good difference with my EJ25. A LOT of other people see good improvement. People should just try the fuels themselves and choose the one they think is best for them. Lets leave it at that.

I agree that any AUDM Subaru should run on 91 fine however. If Subaru advertises/ claims that they will then they should. Most of this fuel debate is pointless because of this point. Running higher octane will just hide the problem. The dealer definitely needs do be pushed to fix it otherwise they will try and fob you off with excuses.

 

[Kevin]

I've always used 95, especially since they introduced ethanol; there was some reasonably well-publicized test on TV not long ago that showed that higher octane was more economical in the long run. No, I don't always believe what I see on TV either! :iconwink: However, it made sense to me at the time.

 

[Ratbag]

Try here for some detailed info:
Octane rating - Wikipedia, the free encyclopedia
https://en.m.wikipedia.org/wiki/Octane_rating#Research_Octane_Number_.28RON.29

Note that Japan uses 90 RON fuel ... :iconwink:.

 

[zippo]

I can see this going back and forth like a ping-pong match ...

My2c worth (and then I'll bite my lip again) is as follows.

1. When I was a young'un, we would occasionally lash out and run some of the green stuff (100 to you GenY's) through our somewhat modified cars (usually higher compression as a starter). Being waaaay before ECU's, we would manually advance the static timing BECAUSE WE COULD. We certainly noticed the difference. (And when we reverted to standard ("super") pump fuel we had to retard it again of course or it would ping like hell).

2. Being able to run more advance without detonation means you can extract more power from the fuel.

3. Any half-decent ECU using a knock sensor should retard the timing long before any driver-detected pinging. If you are hearing pinging in a Foz, something is amiss with that system. NOT the fuel (unless it is eastern european 85 octane) - the SYSTEM. Which needs that problem addressed rather than frothing about the fuel.

Feel free to disagree. That's my view.

 

[Ratbag]

^ Our local Shell servo used to sell methyl benzene by the gallon, loose. We used to use this in varying mixtures with Super leaded (100 octane). In my own case, the car had around 70 thou off the head, and ran very cold plugs (Champion N3) to help prevent knocking. The engine, carbies and exhaust were all pretty highly modified.

It ran like a pig on straight Super, or in traffic on anything, unless it was re-tuned ...

 

[zippo]

Super leaded (100 octane).

Super was never 100 octane, and vice versa.

100 was also a distinctive green (we used to get it from one of those olde preset-pump-up-drain-down bowsers).

 

[Ratbag]

^ It really depends just how old one is, and whether one's memory is completely shot or not ... :iconwink: :lol:.

Try here, about 10-15 paras down in the first column:

https://www.hi-flow.com/HP016aOS.html

The para starts with "In Australia" ....

 

[zippo]

^ It really depends just how old one is, and whether one's memory is completely shot or not

Mine's not shot, short term or otherwise.

The para starts with "In Australia" ....

and then states "high grade leaded Super fuel of 97 / 98 octane rating up to around 100." Bit of a range, and short on certainty.

The stuff we used to be able to get at "normal" servos (Mobil, BP, Shell, Golden Fleece, Neptune, ...) was almost invariably tagged as 97. The stuff I referred to was indisputably 100 (the drums were labelled "100/130" and it was green :biggrin: - big clue there ...). That servo site is now part of a Toyota dealership's used car section, for those familiar with the far eastern areas of Perth.

 

[Ratbag]

Mine's not shot, short term or otherwise.

Hahaha, Zippo. I was referring to mine, not yours ...:lol:.

and then states "high grade leaded Super fuel of 97 / 98 octane rating up to around 100." Bit of a range, and short on certainty

Yes, I read that part too.
In Brissy, Shell sold 100 octane super in my distant youth. I got my licence in 1964, to give an idea of the period I am talking about. The servo at Indooroopilly sold it, and had a 44 gallon drum or two of the methyl benzene out the back. Depending on whose car it was, we all ran different mixes of this plus normal super.

The stuff we used to be able to get at "normal" servos (Mobil, BP, Shell, Golden Fleece, Neptune, ...) was almost invariably tagged as 97. The stuff I referred to was indisputably 100 (the drums were labelled "100/130" and it was green :biggrin: - big clue there ...). That servo site is now part of a Toyota dealership's used car section, for those familiar with the far eastern areas of Perth.

Interesting fact from the Wikipedia article I quoted before is how modern servos generally make up intermediate RON petrol, with the pump drawing off the two underground tanks, one for 90/91 RON and the other for 98 RON. So much for the idea that the 91 RON is rubbish, but 95 RON is fine. 95 RON is almost invariably a 50:50 mix of 91 and 98 RON (approximately ... ).

Also interesting from that last site I mentioned is their statement:

"Higher octane = More power??

Some people believe that adding a higher octane fuel to their engine will increase its performance or lessen its fuel consumption;

this is false

engines perform best when using fuel with the octane rating they were designed for."

Pretty categorical statement. Also accords with my own experience.

As I said before: "Whatever rocks one's boat" ... .

 

[Venom]

Theres been research done that showed by far the majority of people very selectively choose to heed what supports their already established point of view, and discount what contradicts it. Why nuclear power is still a debate decades old and climate change likely to be as well. Interesting read, happened to support a view I had already established... I'll link it when I find it.

 

[Scooby2]

& then enter into the debate... are we actually getting categorically what we are paying for? I believe we very often don't.... and does every variety of fuel vary in its quality in different parts of Australia? Try going to the supermarket and buying Australian fish.... blew me away to find Salt & Pepper Squid.... caught in New Zealand, shipped to China for processing & then sold here.....!

 

[Ratbag]

Gidday S2

That's why I only fill at non-independent petrol stations. For the reasons I outlined above.

What Ross told me about the ethanol fuels worried me greatly. Backed up by Shell getting out of that market some years ago. If your fuel filter is fine enough to remove the crap (10 micron), it will block in minutes. It takes some hours for a 30 micron filter to block, and about a day for a 50 micron filter to block completely. That's plain ugly IMO.

 

[Kevin]

Interesting fact from the Wikipedia article I quoted before is how modern servos generally make up intermediate RON petrol, with the pump drawing off the two underground tanks, one for 90/91 RON and the other for 98 RON. So much for the idea that the 91 RON is rubbish, but 95 RON is fine. 95 RON is almost invariably a 50:50 mix of 91 and 98 RON (approximately ... ).

Then how come a servo can run out of 98 but I can still get 95? :iconwink: