Martin Brown wrote
Rod Speed wrote
Brian-Gaff wrote

I heard a talking head the other day saying that as supermarket fuel is
bought on something called the spot market, it can vary, and is often
quite old and thus its octane value can be depleted.

Perhaps someone can tell me how old fuel loses its octane value?

The more volatile components evaporate off faster.

It isn't just that. Many modern fuel mixes are slightly hygroscopic and
once there is some water in it various esters can form. The upshot is that
old fuel does not evaporate to leave absolutely no residue.

Sure, but that doesn’t affect the octane rating that much.

The ethanol content is particularly problematic in this respect.

Storage of fuel surely has to be nailed by now.

It isn't necessarily economically viable to store
it like that with the cheapest spot market crap.

Even with stabilisers longer term you would need to keep it sealed under
nitrogen to prevent gradual slow oxidation of certain components -
especially when stored in a rusty steel tank.

Yeah, that's what I meant about the economics.

No one is going to do that with the cheapest crap spot market petrol.

Most of the stuff you find on the web about long term fuel storage is
written by deranged survivalists who are nutty as fruit cakes.

Yeah, I've got some that's been in a couple of jerrycans
that I had for the camping trips in the 70s that still
works fine without anything done to it at all.

And that’s in an area where we can get 10 days in a row
over 100F, tho it doesn’t get quite that hot where the
jerrycans live.

"Bill Wright" wrote in message
...
An expert that I trust says that supermarket fuel isn't as good as
other fuel. He says it's all down to the additives.

Comments?