Date: Tue, 11 Oct 2005 02:48:25 GMT From: "James Sweet" <jamessweetnospamail.com> Subject: Re: Premium vs. regular unleaded?
"Dexter J" <lamealameadingdongnospamlamelame.org> wrote in message news:op.syf2eluongtaownospam.eastlink.ca... > Salutations: > > On Mon, 10 Oct 2005 13:16:22 -0300, David Taylor <djtaylornospamoot.com> wrote: > > >> What would happen if I ran my 2002 9-5 Aero on regular unleaded, instead of > >> premium? > > > > I run my 9000 Aero on 95 RON all the time. I don't drive it hard all > > the time, in fact rarely give it full welly for prolonged duration so > > there's not much benefit of burning tanks worth of anti-knocking fuel > > while pootling about! > > > >> My wife thinks it will save us money. I'm concerned it could cause damage > >> to the engine, or at the very least cause enough power drop that you'd lose > >> the cost savings. > > > > I don't believe you'll notice any difference to be honest, only perhaps > > in the cost at the pump. > > > >> Then let's extend the question to her car: she has a 1984 Porsche 911. > >> It's supposed to have premium, and it doesn't have the fancy electronics > >> that my 9-5 has. What happens if she feeds HER car lower-octane fuel? > > > > With a manually set ignition system, it can't retard when knocking is > > detected so it's not a good situation. > > > > David. > > I find that I get better mileage using what passes for high-test here in Canada (94) and see a slight increase on top of that with a carefully measured octane booster. I'm using a 1993 Aero Trionic 5 speed with a home built single stage regulator type boost controller set slightly down from max potential pressure (limits overshoots - but doesn't normally go into the glory zone unless you know about double clutching into lower gears). > > I experimented a bit this summer by adding a substantial amount of legitimate test formula and found that the system couldn't improve timing much above 42.4mpg (smaller Imperial Gal) on the highway - it did start to run a little hotter than norm as the mix was uprated above that mileage figure. Around town was around 25mpg - and again - the engine ran a little warmer. > > I got much more heat by using some decidedly low octane (some very stale pump regular I had in storage) for a couple of tankfuls. But saw considerably lower highway mileage - about 36mpg hwy and 19mpg city. I wonder now if the lower temp engine thermastat and fan controller modification is dictated by lower overall North American octane ratings. > It's not really lower octane, it's just measured differently.
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