I have had both from mechanics we have used…some say RON91 is okay, while others suggest to use RON95 regularly. We have an older (2003) Subaru. They have advised against using RON98 in the engine as it can cause cylinder ignition problems.
However, most mechanics have indicated that E10 over time can lead to accelerated rubber and seal degradation…which is something to note if one uses E10 regularly. There may be some basis to this advice.
I should highlight that the 91 I’m referring to is “Low Aromatic Fuel” - LAF also known as Opal or ‘unsniffable’ … which is somewhat amusing when often in town the other side of the same pump dispenses readily ‘sniffable’ 95 or better.
Some background here including a section titled “Engine damage arising from low aromatic fuel” …
An article recommending that Australia wake up and increase our oil reserves at bargain basement prices.
Meanwhile, back in the US.
An article regarding the disgraceful fuel prices rip-off in Qld.
In Cairns, United is now 108.9 cents/L for U91, a mere 25 cents/L more than Brisbane.
And the quotes of the week from the article.
"KAP Member for Hinchinbrook Nick Dametto said the ACCC’s response was “toothless”.
“There should be more teeth on the ACCC and there’s more that the Federal Government needs to do,” Mr Dametto said.
Federal Member for Leichhardt Warren Entsch said he could smell a rat with regional petrol pricing."
Whilst out today, I noticed an independent Shell servo at 118.9 cents/L for U91.
A mere 25 cents a litre more than Btisbane obviously is not enought for some bottom-feeding grubs.
Different issues:
https://www.couriermail.com.au/news/petrol-prices-the-problem-with-price-dropping-to-80c-a-litre/news-story/50eb3ca25c535710d56a093b6efe6bec
An article regarding petrol having a finite storage life.
The price at the local United for U91 is now 99.9cents/L, the first time it has been under $1/L in decades, whilst the local rip-off independent Shell servo is a mere 11 cents/L higher.
Which is probably part of the reason for the reserve being only 90 days. Stock should, of course, be rotated through the reserve so no fuel is stored for much more than 90 days. Having our “reserve” held overseas isn’t going to make that easy.
The reserve is crude oil which I suspect does not deteroirate as it is in the same state as when it was extracted from the wells.
Is it? I’m pretty sure I saw figures for different types of refined product.
Crude does lose volatile aromatics as it ages. Even the ships that carry it have to deal with the gases that are produced.
While the following is from research into aquatic degradation of Crude the information it contains is relevant to the degradation of Crude over time:
https://www.intechopen.com/books/biodegradation-engineering-and-technology/crude-oil-biodegradation-in-the-marine-environments
“The most important weathering process during the first 48 hours of a spill is usually evaporation, the process by which low to medium-weight crude oil components with low boiling points volatilize into the atmosphere. Evaporation can be responsible for the loss of one to two-thirds of an oil spill’s mass during this period”
Light Crudes have much more of these volatile compounds and the heavier dark Crude Oils have less.
That is from oil spread across the landscape with a huge area exposed to the air which is not comparable to oil in a closed tank. While it is true that crude contains various amounts of volatile fractions these only evaporate at a surface in air.
Huge amounts of crude are stored in oil tankers, ground tanks and old salt mines. I can’t find any useful data (anybody?) on how long it can be there without appreciable degradation but if we are going to speculate my shot is that it is more like decades (or longer) than weeks.
I recall in my university days that if it is sealed (not exposed to the atmosphere), it could last a very long time.
Meanwhile in Country WA its still 1.20
https://www.tandfonline.com/doi/abs/10.1080/01932691.2010.497680
https://www.tandfonline.com/doi/abs/10.1081/LFT-120018527
Heavier (dark) crudes are much more resistant to change but it does happen. Dark Crudes tend to have longer chain molecules which are resistant, they also contain much more Asphaltenes along with other resins and waxes which are very resistant to vapour loss.
Another article on fuel prices.
I loved this part in the article.
"Mr McKenzie said those financial pressures made it very difficult for independent service stations to pass on fuel price reductions in full to their remaining customers.
He also noted most service stations, especially in lower-turnover rural and regional areas, did not immediately benefit from falls in the wholesale price because they got stuck with older, more expensive fuel in their storage tanks.
“Petrol stations don’t pay the spot price for fuel,” he argued.
"They tend to pay a smoothed price based on a rolling average of prices over a two- or three-week period.
“Because we’ve seen such substantial falls, and they’ve been week on week, what actually happens is the rolling average tends to be distorted by the prior weeks and so the price we’re paying for fuel in the ground that people are purchasing … is actually 8 to 10 to 12 cents a litre — depending on where you are — higher than the instantaneous spot price.”
No mention regarding how they increase their prices as soon as the wholesale prices increase despite having the cheaper fuel in their storage tanks.
Taking some of your @Fred123 friendly advice. 
Nearly 50% more expensive if you don’t shop around.
91 unleaded was 81.9cpl in Caboolture on Sat.
Best deal today Tuesday 82.5cpl, Caltex or 7-Eleven.
Worst Deal 3km down the road off the M1, 119.7cpl also a 7-Eleven.
There must be some pain as I’ve seen E10 for up to 10cpl difference to 91, if that is your preference. 76.9cpl best today.
Well this topic has now been going on for three years with no impact on the price gouging, sorry, “prices cycles” by the fuel retailers. Even with the record low oil prices, the retail price is still fluctuating wildly between service stations. Yarrawonga residents have started a change.org petition for a parliamentary inquiry. Any ideas about how we can galvanise the community to effect change?
While oil prices have tumbled, are people still paying to much for petrol? @AndyKollmorgen investigates:
