hi My question is, what happens if you put 98 or 95 Octane fuel into an engine that uses regular, 91 Premium fuel. Has anyone done this before!
sw20,
Apr 7, 7:23am
Your wallet gets lighter.
dent,
Apr 7, 7:24am
Yup people do it all the time. But im guessing less and less as fuel goes up.Most vehicles on the road now days will be able to cope easily with the change of fuel. Some say you will notice better fuel economy and performance but every car is different. Shouldn't do any harm tho.
20498,
Apr 7, 7:24am
+1 and I find it preforms a hell of alot better!
morrisman1,
Apr 7, 7:59am
it depends completely on the vehicle.
richardmayes,
Apr 7, 8:01am
You might get marginally better performance and fuel consumption, but probably not enough to compensate for the premium price of the higher grade fuel.
Putting 91 in a car that needs 95 or better is where the problems usually start.
morrisman1,
Apr 7, 8:04am
a lot of the 'it runs heaps better' will be placebo effect for a basic engine. Unless the car is capable of sensing detonation and adjusting spark in accordance to what it senses then theres going to be no difference between the fuels if its designed for 91.
The fuels contain the same amount of energy but the higher octane fuel has a higher resistance to detonation and as a result can be run with higher compression ratios. With constant compression ratio, the spark can be advanced a bit more with higher octane fuel due to higher detonation resistance. Having the spark occur earlier is more efficient (up to a point) but this feature is usually on later model engines
stevo2,
Apr 7, 8:14am
Well done Morrisman1. Of all the varied and sometimes misleading answers I've read on here in the past, your explanation is possibly one of the best to date. Cheers Stevo
jsbike,
Apr 7, 8:15am
here we go again.
im_andrew,
Apr 7, 10:14am
90% of cars on the road today are capable of this
sr2,
Apr 7, 10:47am
+1 But a well penned, clear and concise answer there Morrisman.
henderson_guy,
Apr 8, 5:57am
But again, it depends on the car. My NZ new, carburetted ute gets significantly better milage from 95 than it does 91, my parents 2001 imported Galant used more fuel when it was on 95, and was happier with 91. So my best advice is, test it out. Record your fuel usage, when you fill up each time, calculate how many KM's you have done. Then, change fuels and record it again, and compare.
girlracer2005,
Apr 8, 6:20am
my 92 subaru runs better on 95 then 91 but around town ive been running 91 due to cost even tho i lack power on it but will only run 95 on trips out of town now
richms,
Apr 8, 8:39am
I would sooner give up coffee than use 91 to save a few dollars a week.
jasongroves,
Apr 8, 10:08am
My advice is.run the fuel that is recommended by the manufacturer;)
johnf_456,
Apr 8, 10:12am
91 will not save you, you may think its cheaper at the pump put do a km per tank test and you will find 95 to be better I'm sure including the extra price with the 95. Try it depends on the car but I'm fairly certain it will if you say it runs better on power with 95.
jasongroves,
Oct 11, 6:52am
What model/engine Subaru!
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