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petrol usage

Author Topic: petrol usage  (Read 9463 times)

OzBenzHead

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  • Location: Northern NSW, Australia
Re: petrol usage
« Reply #45 on: 04 October 2009, 12:56 AM »
[...] Normally we do ?L/100km in Canada, but my car is American spec with American dials. So miles used for trip computer.

Same in Oz: litres per 100 km -- though all but one (W201) of my Benzes have mile speedos / odos, so a degree of conversion is necessary.

Don't know about compression, it's a 1974 model in US-spec. So I'd assume low compression.
I use 91 Octane fuel, as the owners manual recommends. In my country, the only octane ratings higher than that are 92 and 94.

Yep, I expect it's low-comp. And I believe the US (possibly all of NA?) octane ratings also don't match ours. Perhaps 91 is recommended, but in Oz ratings I'd go for the better fuel. My cars return better distance per volume on our 98 RON than on lower-octane fuel -- enough to more than cancel the price difference. And the additives in the higher-rated fuel also (allegedly, and my experience tends to support it) keep the entire fuel system cleaner and happier.

I'm also fortunate that none of my Benzes (except the W201) have catalytic converters of other allegedly anti-pollution equipment -- they are a mix of Oz- and Euro-spec, all high-comp.

We have 91, 95, and 98 RON grades. The 91 is bats' pee.  :P

flutes

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Re: petrol usage
« Reply #46 on: 21 October 2009, 01:23 AM »
After a completely non-scientific test of AU "premium" (98RON) the fuel gague is at about half and I've done about 300kms.  This is about 100kms higher than it usually is at this point.

I'm shocked (SHOCKED!) at the difference in fuel efficiency with regular vs premium.

Australian petrol = US beer.
Matt
1977 450SEL

Big_Richard

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Re: petrol usage
« Reply #47 on: 21 October 2009, 02:08 AM »
US fuels are FAR lower quality than what we have become accustomed to in Australia, and Western Australia has the highest quality fuel in the country - most notably BP. It costs more, but as with everything its worth paying more for something decent.



TJ 450

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Re: petrol usage
« Reply #48 on: 21 October 2009, 02:29 AM »
I might add that using anything less than 98 RON in a 116 is a false economy. Yes, it will run, but performance and mileage will be poor. It is therefore more expensive, IMHO. ;)

Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

oscar

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Re: petrol usage
« Reply #49 on: 21 October 2009, 03:13 AM »
Western Australia has the highest quality fuel in the country

I've heard this before - why is it so?  Where does the stuff come from?
1973 350SE, my first & fave

flutes

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Re: petrol usage
« Reply #50 on: 01 November 2009, 12:56 PM »
OK so some numbers are in, and are they surprising.

In the weeks since I've changed to 98 RON I've consistently achieved around 30% more Kms from the same amount of fuel. This has been across a mix of driving conditions (70% city, however) and with all other factors being more or less equal.

Next step - blow the cobwebs out see post - and see what difference that makes.
Matt
1977 450SEL

arman

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Re: petrol usage
« Reply #51 on: 02 November 2009, 12:12 AM »
I always use RON98 for my '74 450SEL. But I'm beginning to understand that that is not a guarantee for good gasoline.
I was on a long trip with my wife and kids from Sweden to Germany via Danmark. Somewhere on the way back I had to fill up with gas. Now today it is not so easy anymore to find RON98 at gas stations in Northern Europe.
I got a tip from a pedestrian to find a SHELL station some kilometers off the highway.
There I found they had SHELL V power which is RON99 and especially developed for (modern) high performance cars. It is said that this is the only gasoline which is transported to gas stations 'as is'. I mean they don't mix  the stuff with additives at the station which is probably normal then for the other types of gas.
I know they mixture with additives like ethanol and white spirit in normal gasoline depending on winter or summer weather.

Now I'm generally not impressed by -in this case Shell's- marketing drive for SHELL V-power. That means that I tend to be suspicious to marketing tricks.
Normally I get 600km out of a tank and then I fill it up with 80-83 litres when I drive steady highway speeds of 110-120km/h. Now with SHELL V-power I'm already over 600km's and I have not been driving on the highway alone! The reserve light is still not on! (and it isn't broke, because it worked when I drove down the steep slope into the garage :)).

Of course Vpower is even more expensive as RON98 but when I fill up the tank next time I will report the economical calculations and get back to this thread.

An other thought came up to me and that is that when I park the car for the winter, the best thing is to fill it up with gasoline. Gasoline deteriorates a little bit has been said over here. Well, even if SHELL V power is not economically justified it is probably a very 'clean' gasoline and it would maybe be a good idea to empty your tank of average RON98 and fill it up with 20 litres of Vpower that can sit there 'till next spring?

(this is not a disguised commercial, I just wanted to let you people know about my experiences... )
« Last Edit: 02 November 2009, 12:17 AM by arman »
1974 W116 450 SEL 340.000km
Black exterior (040), olive green velours interior (966)
http://gallery.w116.org/v/show_room/Armans450sel/

OzBenzHead

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Re: petrol usage
« Reply #52 on: 02 November 2009, 05:35 AM »
Arman and other interested parties:

A salutary lesson in false economy (cheap fuels)

You've probably read my rants before on the sense of using Oz 98 RON in my Benzes, so I'll not repeat my own words -- rather I quote from the latest Super Star (MBCQ magazine, p 26; the article is unattributed):

A Benz factory-trained technician's tale of warning about low-octane fuel.

Quote
Complaint

A 2001 C180 coupe was towed to the service centre with the complaint that it would crank over but would not fire.

This was a car that had travelled only 100,000 km and had been meticulously cared for by its one owner from new. It had had all of the scheduled and required services throughout its life and is a well presented motor car.

Cause:

The car was found to have very low compression on three cylinders, caused by low octane fuel which caused carbon to build up between the rings and the ring land.

Correction:

The following work was required: the engine was removed from the car and the cylinder head, lower sump and pistons were all removed.

The pistons were cleaned, new rings and bearings fitted, valve stem seals renewed and the head was pressure tested.

The engine was reassembled.

Cost of repair: Approximately $5,800.00.
[...]

Over the vehicle's life [...] the owner may have saved around $1300.00 by buying low octane fuel.

So the fuel cheapskate was at least $4500 worse off that he should have been had he used 98 RON. (This is an Oz story.)

OzBenzHead

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Re: petrol usage
« Reply #53 on: 02 November 2009, 05:38 AM »
Oh and BTW: Wherever possible I fill up with Shell V-Power -- 98 RON in Oz.

There are only two trusted 98 outlets in my town, and the Shell is far closer to home.

koan

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Re: petrol usage
« Reply #54 on: 02 November 2009, 12:37 PM »
A salutary lesson in false economy (cheap fuels)

Not so sure about this story OBH.

Why would a low octane fuel cause more carbon build up than higher octane fuel? This implies any vehicle designed to run on low octane fuel is going to suffer the same fate. That an injection problem putting in too much fuel or cheap fuel shandied with some unknown hydrocarbon might cause carbon build up I can understand but not just low octane fuel.

As far has higher octane fuels developing more power in 116 engines it depends on how the engine is adjusted.

The amount of energy (BTUs/lb or whatever the metric measure is) in low and high octane fuels is much the same, the difference is the anti-knock value allowing engines to have higher compression ratios and run with more ignition advance.

Put any octane fuel in a modern engine and the management system will adjust the ignition to prevent knocking/pinging. Higher octane fuels will let the engine develop more power because the computer can wind more in ignition advance to just before pinging starts than it can with a lower octane fuel.

But our old technology, pre-computer, low compression engines have fixed mechanical advance. If the engine is designed for a particular fuel grade and set set up to run on that fuel just filling up with a higher octane fuel is not going produce more power because there is no difference in the energy in the fuel.

Only if the static ignition timing is advanced to take advantage of a higher octane fuel's resistance to pinging will it develop more power.

Now having said all that the last couple of fills have been 98 fuel. Not done any economy calculations but kms covered and fuel gauge readings do suggest I might be getting better economy with this fuel. I'll you know.

koan

Boogity, Boogity, Boogity, Amen!

Mforcer

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Re: petrol usage
« Reply #55 on: 02 November 2009, 02:30 PM »
I agree with Koan.

Generally, higher octane fuels are better quality. It is just easier to market a higher (octane) number.
Michael
1977 450SE [Brilliant Red]
2006 B200