Canadian gas station Octane levels for M5

[speedemn]

Though the label on the inner side of the gas lid says "min 93 Octane" there is a relatively limited number of stations here where we can get above 91 Octane. The main options from the major brands are Shell 91 Octane (no ethanol) or Esso 93 (which contains some ethanol) or Sunoco 94 (which contains 10% ethanol) - sold through Petro Canada.

On my previous stage 4 Dinan E39 540i I found that Shell 91 not only burned the cleanest (likely due to no ethanol plus whatever Nitrogen enriched cleaning system it runs) it also gave me better gas mileage (again likely due to no ethanol). That motor was at 529K kms before I sold the car with the motor still perfect!

I am wondering which would be best on the F10 M5... on the E39 540i I assume that recommended Octane level to run was 91 (I don't recall now) so of the various options the 91 performed the best. On the M5 which recommends 93 am I better off to run a 93 or 94 that contains ethanol (which just burns off and I am assuming not as clean as Shell V-Power 91) or would running Shell 91 decrease any sort of performance given the lower Octane level?

Has anyone done any research on this or had any experience on their own F10s?

[F10MFive4Life]

Have not done research, but I can say that I didnt notice any difference in fuel economy on the one full tank of Shell 91 that I filled up a few months ago, so I've been sticking with Petro 94. From what I remember it's always best to go with higher Octane with higher performance cars like ours. With lower octane, you'll sacrifice performance (HP/Torque) Maybe someone with more knowledge can chime in.

[M5Rick]

Originally Posted by F10MFive4Life

Have not done research, but I can say that I didnt notice any difference in fuel economy on the one full tank of Shell 91 that I filled up a few months ago, so I've been sticking with Petro 94. From what I remember it's always best to go with higher Octane with higher performance cars like ours. With lower octane, you'll sacrifice performance (HP/Torque) Maybe someone with more knowledge can chime in.

Lower octane than normal can induce the dreaded 'knock rattle'. Not sure what 91 and 94 octane equals in Canada but over here it's 99 Octane for M5 which is RON,Research Octane Number.The higher the octane, the more compression the fuel can withstand before detonation.
Using a lower octane rating than recommended for this engine is promoting risk.

[speedemn]

Originally Posted by M5theonlyone

Lower octane than normal can induce the dreaded 'knock rattle'. Not sure what 91 and 94 octane equals in Canada but over here it's 99 Octane for M5 which is RON,Research Octane Number.The higher the octane, the more compression the fuel can withstand before detonation.
Using a lower octane rating than recommended for this engine is promoting risk.

All gasoline above 91 Octane contains Ethanol. What I am wondering is the fact that since ethanol equals octane but ethanol attracts water which theoretically can cause fuel system damage; also contains alcohol which causes corrosion.

But speaking of 91 Octane from Shell specifically they advertise it to be Nitrogen enriched which is better for keeping the fuel system clean.

So what I am wondering is whether the higher octane gas grades available from other providers is in fact better in the long term for our vehicles and if there is in fact a performance difference (not perceived due to the fact that the other gas options are stamped with a higher Octane on the label).

[M5Rick]

Originally Posted by speedemn

All gasoline above 91 Octane contains Ethanol. What I am wondering is the fact that since ethanol equals octane but ethanol attracts water which theoretically can cause fuel system damage; also contains alcohol which causes corrosion.

But speaking of 91 Octane from Shell specifically they advertise it to be Nitrogen enriched which is better for keeping the fuel system clean.

So what I am wondering is whether the higher octane gas grades available from other providers is in fact better in the long term for our vehicles and if there is in fact a performance difference (not perceived due to the fact that the other gas options are stamped with a higher Octane on the label).

Personally I would not use the Shell 91 then if 93-94 is recommended.You can always add a fuel additive like Redex,which is what I use to protect fuel system,lower emissions and keep injectors and plugs sweet.