Australia still has four refineries. While probably not enough to keep the whole economy moving in a war, its a significant amount. Storage doesn't last for ever particularly for refined ready to use fuels.
We certainly have plenty of energy, just not as oil. We could convert many vehicles to natural gas or LPG. TBH we are probably better off focusing on moving buses and trucks to natural gas, improving rail, encouraging better fuel usage. We also produce Ethanol and biodiesel, while small amounts currently in a war time situation, many vehicles can run on E85.
We could also produce hyrdocarbons from coal, which might have a bit of a longer term future, if fuel oil decreases, this could provide a way to source lubricants, tars, etc.
Fuel degrades with time. E10 is useless very quickly as it absorbs water, you shouldn't put it in anything that you are going to let sit for more than a week or two. Its illegal to put into aircraft and not recommended for boats. Water is a constant problem for fuels. humidity in the air can condense out over temperature changes and water causes lots of problems. The octane rating tends to decrease with time. For diesel the lower sulfur content tends to shorten life more than what was historically the case, as the sulfur has a biocide property.
Its questionable to have massive fuel storage far away from a refinery.
Given the low price of oil and the glut and the long term future, building more refineries probably isn't a realistic solution. Australia really doesn't have any new nearby oil fields unless we go down the expensive (and now probably unprofitable and environmentally damaging) fracking process. Even then I don't think we have enough water to start fracking..
Australia has a relatively small military. The oil use is not that significant compared to the economy. The recent COVID19 situation shows that in some situations, Australians can work from home and significantly reduce their fuel use. Domestic travel can be limited and that along a few other restrictions would allow all the jet fuel we would ever need for our military.
Ultimately if our oil supply is cut off from the middle east, Singapore and the US, we have a much bigger problem than oil supply. It would mean we are losing a global war.
Personal storage of fuel doesn't really make a whole lot of sense..
Here's a cautionary tale about the amount of energy packed into common liquid hydrocarbon fuels - and why you need to be immensely careful with them if you store even a small quantity of petrol - say five litres - in the home (say for the mower). At 11.28am, Saturday 12 August 2000, a m
autoexpert.com.au
Inside a house its usually 5 litres, inside a garage its usually 25L, inside a shed away from houses/boundary its up to 250L (rural location etc). 25L won't get people through a normal week driving two cars. Even if you had 100L, you are still probably talking about a few weeks for many suburbanites. Preppers generally don't even bother try hording fuel. It is probably easier to gasify wood (for say a generator) or go solar or go without etc.