Chelseaa4a

Hi guys…quick question for my Canadian S class friends. My dad’s old S550 recently arrived here in Quebec after shipping it from Victoria BC. Of course I plan to run premium fuel but I’m just curious what others are running. I think my dad used to run 94 from Chevron but it’s hard to find anything locally above 91 where I live. Sorry if this sounds like a silly question…just curious what others run or have been running. Is 91 acceptable or should I be running something higher? Many thanks in advance.

BOTUS

fuel filler flap should have a sticker on the inside stating what to use

in the UK they have just moved to destroy your car 10% ethanol (it absorbs water, causing corrosion on fuel pumps, lines, injectors etc, breakdowns with time, rots plastic and natural rubber, and incredibly allows bugs to grow in there that eat metal !!!
The premium stuff by ESSO is ethanol free - but very pricey

my car's fuel consumption fell off a cliff with 20% increase in fuel consumption when E10 (euro name for 10% ethanol crap) came in. It should lose 6% as ethanol is less energy dense -
they ONLY use to
1) to make cars die faster,
2) as a budget fuel octane improver

I have gone back to posh stuff and MPG has improved 10% - but I'm still not where I had been. NOTE: cars adjust themselves to the conditions, fuel quality and wear and tear etc. I wonder if I should wipe these adjustments (called adaptions) and see where it lands

Can't advise on octane as USA used a different (AKA wrong) set of measurement to the ROW

TopGear007

I'm running 91 from Shell. It is ethanol free and it's fine.

Chelseaa4a

Thanks…good to know.

Senecat

M273 is NA, so run whatever you can get away with. M278 and any other boosted car requires higher octane for detonation purposes.

I'm M278, so I run premium (93), which by the way, is $4.49 as of today, here in Tampa.

nath_h

Premium 91 octane is the best we have in Iowa...no problem running it.

Chelseaa4a

Thanks

WHPH28

Running 93 only here. We're $5.25 gallon these days.

MBCO

Costco premium 91 octane is what I use, it’s a Tier One fuel, no ethanol.

WRC-LVR

Premium 93 here in Atlanta as of today is $4.95 ~ 15% ethanol

lkchris

In the USA, the octane shown on the pump has a fairly direct relationship to the altitude at which the station is.

It's more likely to be 91 for premium in Colorado and 93 for premium closer to sea level.

Of course there is no octane needed dropoff for a turbocharged engine, but you'll just have to live with the adjusted power.

RichDMB

I have the M273 engine in my 2008 S550, can I get away with 89 octane? Don't flame me for asking, but I do want honest opinions. There is a 60 cent differential between 89 and 93 octane, so that's a $14 difference per tankful, or $750 per year if you tank up weekly.

WHPH28

What does it say in the inside of your gas flap? Some run regular and mid grade and experience no issues. I only run 93 but I'm M275 but in both of my S550's I ran 93 as well. Gas here is now 5.11 gallon.

BOTUS

wow dangerous rubbish

ethanol
destroys natural rubber
deforms / expands and ages plastics, causing cracks and leaks in certain older petrol tanks
is hygroscopic (absorbs water) leading to rust and corrosion - leading to holes in metal tanks and debris blocking fuel lines
grows bugs that excrete acetic acid causing pitting and erosion of fuel injectors, pumps and engine components (particularly so if used infrequently over winter)
starts to break down and age in 2 months vs equiv of 2 years for normal petrol
has a lower energy density leading to increased fuel consumption

at 15% its should run badly - many older vehicles were not set up with a engine management and fuel system expected to see that filth on a regular basis

BOTUS

out of interest re Octane rating

most of the world runs on RON (research octane number) and its an ancient test that runs something that is NOTHING line a modern engine to determine the point at which knock occurs (damaging explosion - rather than the extremely rapid burn petrol engine's need)
USA run a better test MON (motor octane number) and should be the right way to do it - but it ends up being an outlier and just confusing for the rest of the world - as we end up working with fuel that is much the same (in knock prevention) but yours is just 2 thingys less nearly all the time

Senecat

You drive a Mercedes. Suck it up!

Senecat

$4.98 for 93 today here in Tampa.

Timo Schroeder

I use Shell V Power Racing 100 every 4 refuelings. Sometimes I refuel 95 octane, and add a fuel additive from Danish ABCON / Lindemann which gives almost the same result as with Shell Racing 100. And, there are significant differences in how many kilometers I drive on a refueling about + 170 km., And a very nimble car.