So my car requires premium fuel but lately that’s become eye waveringly expensive since our inept government won’t lower fuel excise to compensate.
So I’m thinking I might put in 1/2 a tank of 98 and then half a tank of 91 or e10. Would this give me a useable blend of fuel with an octane rating somewhere between the two?
Its a jeep cherokee kl (2.4 tigershark)
Can I Deliberately Mix Fuel Types to Save Money
No, but you can accidently mix fuel types for any number of other purposes.
It didn't end well when the police used the wrong fuel.
https://www.gizmodo.com.au/2014/02/nsw-police-destroy-patrol…
So much bullshit in that one article.
blend of delicious unleaded petrol and nasty ethanol.
Ethanol is not "nasty" and is cleaner than fossil based fuels and is renewable.
the low-quality fuel cracked the engine block.
This is not what causes engine blocks to crack. Pinging a car off it's tits and driving it like a highway pursuit vehicle does.
The Ford FPV GT has a recommended fuel type of 95RON. E10 is 94. It wasn't the E10 that killed that car, it was the nut behind the steering wheel.
And added to all of that, you are comparing an extreme duty cycle pursuit police vehicle with OP's Jeep Shitbox.
Bloody hell was that "article" written by a child?
Cracked the block, but only $5k of repairs? And even if the wrong fuel was causing pinging, the knock sensors would have caught it and retarded the timing.
It’s a ford engine. Their blocks are a dime a dozen
@Euphemistic: Its the Miami 5.0L block, they are not a dime a dozen. I've been a Holden supporter most of my life, but even I appreciate that the Ford 5L Coyote engine is a nice piece of gear.
Ethanol is not "nasty" and is cleaner than fossil based fuels and is renewable.
Not according to this.
Corn-based ethanol found to be worse for the climate than petrol, says US study
https://www.euronews.com/green/2022/02/16/corn-based-ethanol…
Did you also read the article that breathing will kill you because of all the pollutants in the air?
Stop breathing!
problem with the car's tune from what I read: http://www.fordforums.com.au/showthread.php?t=11413274
It depends on your car. High performance vehicles that require premium fuel will burn through 91 very quickly so you might end up spending more
That's not how octane ratings work
Higher octane doesn't mean you need less than a lower octane fuel
Nope - if you run a modern car optimised for high octane fuel with low octane fuel you won't damage it because the ECU will automatically retard the timing to prevent knocking. But the later spark timing means lower burn efficiency, so you use more fuel for less power.
But if you run a car designed for lower octane fuel with high octane fuel the timing will be unchanged so you get the same efficiency. The only difference is you'll be paying more per litre.
because the ECU will automatically retard the timing to prevent knocking
How does the ecu know to retard the timing?
@brendanm: Lower octane fuel than specified by the manufacturer (based on the factory tune) will lead to early detonation (aka knocking). The ECU will detect knocking with a knock sensor and, as a compensation strategy to prevent knocking, retard the timing.
@dazeller: Sorry, it was a rhetorical question. The engine has to experience knock for the ecu to pull timing. Every time it puts timing back into it, it has to knock before the ecu knows to pull timing again. It's a safety. The engine is still knocking, just not as often.
For those that don't know… fuel excise is about 44 cents per litre which we also pay 10% gst on as well.
You've also paid income tax on the money that you are using to pay for it, hooray! Tax on tax on tax.
And taxes to pay government support for the person taking your money.
Good.
The more expensive oil gets the fewer cars on the road.
Just don’t get fuel from United is my advice working in the industry.
Please explain
no credibility
please explain. They are pretty much the only one providing e85
I think lowering fuel excise is a bad idea. Using fossil fuels is bad, especially when you are using them in an inefficient car instead of an efficient power plant. Is it proper for the government to do something which makes you want to burn fewer fossil fuels and incentives you to finally get an EV. And besides Australia once rationed fuel due to a war in Europe during WWII and WWI, I mean probably they did I don't know where we got our fuel back then but you'd think it would be rationed here too.
The progress to renewable or cleaner alternatives in Australia is abysmal/non-existent, almost like the government has some sort of incentive to stay with fossil fuels.
The majority of voters appear to want clean energy alternatives, but I guess the current government serves the fossil fuel industry over us. Also some rubbish from Scrotmo about EV's ruining the weekend.
since our inept government won’t lower fuel excise
Cute, it should be significantly higher if anything
Why do you think that?
Because they don't understand that this awesome world we live in is enabled by fossil fuels
The amount of negs you get for pointing out facts is ridiculous
Just switch to 91 completely.
Best way to save money on fuel is not to drive. Second best way is not to drive so fast.
Second best way is not to drive so fast.
You will use much less fuel driving constantly at 100 kph than doing 60kph in stop start traffic…
Ok. Not to accelerate so fast, particularly in stop start traffic. There no point racing to be first to the next red light.
What about keeping you foot on the accelerator until the last minute and breaking hard when you need to stop?
@Euphemistic: Anything is driving faster when you compare to being parked.
It doesn't mean it's a good example.
Yes, and you'll use even less constantly driving 90kph instead of 100kph. Why are you comparing stop start traffic with being on a highway?
Probably because someone mentioned driving faster costs you fuel. But HiGhWaY Is FaStEr.
You can use the different octane fuels together. But note the higher octane is slower burning making it easier for the car to time the ignition for combustion and helps prevent pre ignition. This means a higher octane fuel can sometimes be more efficient. Do a bit of calculating to see if it's worth the extra money.
My car has 95 recommended. I use 7Eleven Mobil E10 which is 94. The computer takes care of the rest. Also many United’s E10 is 95. Cheapest price every time. Had my car for 7 years and it’s a four litre turbo. Purrs like a kitten, a lion kitten that is😉
Your engine timing should adjust to the octane level, but there are limits. This is why you need to post what the actual engine is.
This is why you need to post what the actual engine is.
They have. They have a KL Cherokee. Both petrol engine options take 91. No idea why op is using premium in a normal compression, naturally aspirated engine.
Agree. At my local servo I see people putting 98 in their 15 year old camrys and I just shake my head.
Energy density of E10 is lower than 91/95/98. You're better off filling up with 95 (if your engine is rated at that level). You'd get the cost benefit of not using 98, with the added benefit of getting more energy when it combusts.
You really should be using the recommended RON level for your engine. You stress the engine out if you use lower, and you're wasting money if you use higher. RON is not a measure of energy. It's a measure of compression ability. If you compress your fuel-air mixture more, the resulting ignition will have more force. Which is great if your engine is designed for that. The engine needs to compress at 11:1 or higher to get a benefit from 98.
Only other benefit of 98 are the cleaning additives. That might be a reason to fill up with 98 on occasion (once every few months). The actual benefits of this aren't particularly studied well (as far as I know). Good way to market your product though, and would be a tipping point for people that want to convince themselves that they need to use the most expensive fuel available.
If your car has a PPF (petrol particulate filter), do NOT touch E10 or 91. The higher sulphur levels will damage the filter, and that expense will be much more than any saving you will get.
Energy density of E10 is lower than 91
Maybe not by much
https://www.ozbargain.com.au/comment/11870538/redir
Not only that, you need to test your own vehicle by measuring fuel consumption as well. I found there was no consistent difference between 91 and E10. And you cannot rely on ‘it runs so much better on xxx’ unless you’ve measured it accurately and repeatably because seat of the pants measuring means nothing.
That comment doesn't really talk about energy density of ethanol. Though it did mention that it was common to find ethanol in regular unleaded. That was interesting.
Anyways, you're kinda right. Ethanol itself has around 30% less energy than your normal hydrocarbon mix in petrol. But 10% of 30% makes around 3% less energy found in E10, theoretically. It's not huge, but it does narrow the difference between E10 and 95, as far as cents per km is concerned. With the added bonus that you don't have to worry about water absorption and phase separation by the ethanol, which could cause issues for your tank if you don't burn it relatively quickly.
Where are you getting the 11:1 figure? My car has the 2JZ non turbo motor and I put 98 in it, and it has a compression ratio of 10:1. The turbo version of this motor (the famed 2JZGTE) runs a 8 or 8.5:1 ratio, and I would really hope no one is using less than 98 in theirs.
Today, the average high-performance street or strip turbocharged four-cylinder race engine sports a compression ratio of 9.5:1.
Fill up to whatever your minimum requirement is. If it's 91, run 91. If it's 95 - run 95. No point mixing something as that will make it more expensive for no reason.
If you want to spend 10k in replacing the engine…. go right ahead
So my car requires premium fuel
No it doesn't. You are a victim of false information.
Just build your own dreams
Your engine is tuned to run on a specific minimum RON rating. When you drop that, the engine, assuming it has a knock sensor, will adapt the timing internally to deal with it. While it does mean the lower RON is accepted by your engined you may find a drop in efficiency, and this will ultimately defeat the purpose of you running 91 - you may save money at the pump but you might at the pump more frequently.
I have no problem mixing gas and fusion, but YMMV.
The RON rating also implies the standards for sulfur and particulate contamination allowed in the fuel.
98 and 95 fuels are the same standard. Switch to 95. The engine knock sensors should compensate the tune after a few tanks.
91 fuel has much higher limits on the amount of sulfur allowed, if you actually need 98 for your engine, do not use 91.
E10 fuel should only be used if specifically mentioned in the user manual
After a few tanks?! Surely it's pretty much immediate? A few tanks would mean drive 1,000 km with knocking.
Tell us what car you have in title please!
Jeep Cherokee 2.4l tigershark
half 91 and half 95 is perfect if you are not towing. Forget e10.
I'd be putting fuel efficiency much higher on your list of requirements for the next car purchase…
Use 91. I didn't think anyone would buy the anaemic 2.4L.
I didn't think anyone would buy a Jeep these days based on their history of reliability.
@zeomega: Well yes, they aren't the best choice, however the pentastar V6 is actually quite a nice engine.
In my view it depends how old the car is. The reason for the high octane fuel is that its required in high compression engines.
Overtime as engines wear, they lose compression.
In my car with 200,000 kms on it that requires 95+, I alternate between 95 and 91 (more often 91 lately). I'm also not really concerned at this point if I could be feasibly doing damage to the car.
I never use ethanol fuel though.
If I had a newer low klms car I'd only use 95+
As long as you dont mix diesel and petrol
you drive a jeep…..mixing fuels is the least of your worries
Yes you can mix.
Surely your car doesn't require 98? That's pretty much only the highest of high performance engines.
The majority of cars run perfectly on 91.
I would check your manual regarding octane level as looking on line it appears to me that the recommended octane for a 2.4 tigershark is 91RON or U.S 87 not premium
Why doing it? fix the engine could cost you 2-3 years fuel
Normally I'd say you can safely drop 1 grade of unleaded with no issues as the car ECU has factored in safety margins to cope with occassional dodgy petrol.
However Jeep is not a brand known for honouring warranties or recognised as the most reliable car maker. If you have a new car and its still got warranty then I recommend not giving Jeep any excuse not to honour your warranty.
I've flashed my own car ECU before and studied the ECU maps. If you are super geeky you can do your own "data logging" and verify your engine isn't detecting pinging. The ECU logic is pretty simple if engine detects knocking it will detune the engine, will retry full settings in 5 minutes, if that fails will wait longer to retry in an hour, 1 day, 1 week, etc. So with enough time your ECU will safely and permanently adjust to lower grade fuel.
Only consider downgrading your fuel if you are commuting. Don't do it if you are street racing, towing or highly variable temperature environment. The lower the power and stable the environment the more your ECU can adjust.
I wouldn't mess with it… the difference is what like 10c a litre.. .not worth it if it damages your car.
Having a jeep they have enough go wrong without you adding to the problems.
You could probably use vodka. I imagine there will be plenty of that.
My cars only take electricity (from the sun) for fuel.
If necessary, you can mix your solar fuel with coal fuel to increase the cost. Won’t harm your engine as long as it has an amp sensor fitted to retard the charge timing.
Honestly if your car is meant to run on 98, I would assume that this car is a performance car of some kind, then the lowest I would personally go is 95. If you use 91 or 91 + ethanol and its greater than 10% i would be very be worried for the cars engine internals
https://youtu.be/eHE5wo6XPf4