High octane petrol - should I?

[peterbredde]

Hi. Following on from a point made in another thread, I am wondering, should I continue to use high octane? What are the benefits? Any drawbacks?

For clarity, I am running a new 5.0 V8 Mustang. I only ever use high octane. Don't know why - I think the dealer recommended it.

Thanks

[kambites]

The engine will have been tuned to run on a certain Octane, run it on (at least) whatever the manufacturer recommends.

Some engines can adapter and will produce more power on higher octane fuel. No idea of the Mustang engine is one of them.

[Vladimir]

Jap cars often need high octane because that's what Japs generally have available.
Yank fuel is pretty low grade so I suspect you'd be better off with normal juice. I also think only highly tuned turbo'd engines need super, NA engines are fine on normal fuel. But check the manual - it'll recommend a certain grade.

[KTF]

Put in whatever it says is required in the handbook. Anything else is a waste of money.

[J4CKO]

Vladimir said:

Jap cars often need high octane because that's what Japs generally have available.
Yank fuel is pretty low grade so I suspect you'd be better off with normal juice. I also think only highly tuned turbo'd engines need super, NA engines are fine on normal fuel. But check the manual - it'll recommend a certain grade.

Not always true, 350Z requires Super.

[kambites]

J4CKO said:

Not always true, 350Z requires Super.

For what it's worth it certainly doesn't require super (except possibly if it's an import) - it's a requirement for EU type approval for a car to be able to run happily and pass all emissions tests, etc. on 95RON.

Of course the OP's far isn't type approved, but I'd be amazed it it wouldn't run on 95.

[Vladimir]

J4CKO said:

Not always true, 350Z requires Super.

I bet it would be fine on normal although it IS a Jap car.

[scotty_d]

Vladimir said:

Yank fuel is pretty low grade so I suspect you'd be better off with normal juice.

Misconception it is measured different to ours like our gallons and a "US gallon"

[Spoof]

As with the Z, the E63 AMG filler door recommends you use 98 too. That's the 6.2NA, not the newer biturbo. I'm sure 95 is fine, but I like to know its not losing some power (be it maybe 3 or 4 hp) for the sake of being a tight arse at the pumps.

[Spoof]

scotty_d said:

Vladimir said:

Yank fuel is pretty low grade so I suspect you'd be better off with normal juice.

Misconception it is measured different to ours like our gallons and a "US gallon"

Its still generally lower grade even when converting MON / RON / PON

Edited by Spoof on Monday 16th December 19:28

[Vladimir]

scotty_d said:

Misconception it is measured different to ours like our gallons and a "US gallon"

No it's not. Its a well known fact. More so with diesel but also with petrol.

[J4CKO]

Vladimir said:

J4CKO said:

Not always true, 350Z requires Super.

I bet it would be fine on normal although it IS a Jap car.

There have been reports of engine bother on cars run on normal, ok if you dont use it as intended but if you do it needs the higher octane, theydont make quoted power on normal either.

[Spoof]

98 RON is about 94 PON. It was near impossible to find that in Phoenix when I lived out there.
91 was premium and that's about equivalent to our 95 RON I believe.