Regular Vs Premium unleaded

TONX_2

Morning All

What opinions do you guys have on regular Vs premium unleaded.
I tend to stick with V power or BP ultimate, but wanted to know your thoughts and experiences, mostly around mpg, performance or engine cleanliness….

Some other forum links
https://www.m5board.com/vbulletin/e39-m5-e52-z8-discussion/159631-95-vs-99-octane-dyno-graph.html

foxy-stoat

Despite what you may or may not have read or know, the biggest single factor that influences MPG fuel economy is your right foot, not fuel, not turning the air con off, not removing the rear seats.

Using high RON fuel may help modified turbo cars from pinking/detonation - some high performance cars state they need higher RON fuel in the handbook, I had the displeasure of owning an E46 M3 for a few months, made no difference whatsoever switching fuels apart from it cost a bit less at the pump.

As for "cleaning" the engine - if you ran 2 identical engines for 100,000 miles using identical trips, identical service intervals and opened them up, I doubt you would see any measurable difference internally - but would be a good experiment.

I can 100% guarantee if you had a pair of 1.2 Vauxhall Corsas side by side one with standard fuel and the other with super plus or whatever, they would still get to their destinations the same time.

neilmcl

Do a search, it's been discussed before. End of the day it all comes down to the type of car so if you're trying to steer a thread into talking about alleged "performance" cars then I'll give it a miss.

AdrianC

Firstly, the vanilla 95RON is "Premium Unleaded". Look at the pump. Be VERY careful about US and European differences in terminology and the way in which octane is measured.


There are five European standards for unleaded, three of which are unchanged since the introduction in the 80s.
(Regular) is 91RON. It was never available in the UK, and has pretty much disappeared from those countries it was available in.
Premium is 95RON.
Super is 97+RON.
All are 5% ethanol, E5.

Then there's 10% ethanol, E10, 95RON - it's been available in other European countries for a decade or more, and is coming to the UK soon alongside E5 95 and E5 97+. All US unleaded has been E10 since the 70s. All new cars in Europe since 2011 must be fine on E10 95.

Finally, there's 85% ethanol, E85. Again, not available here, but popular elsewhere in Europe. You need a specifically-mapped car to use it.


As for 95/97+, it entirely depends on whether your engine can take advantage of the octane difference. Some - mostly high-performance - will. Most won't.

I'd suggest that a 4% peak power difference on something as fast as a BMW M5 - even a 20yo one - is utterly irrelevant on the road, and even on the track for all bar a very tiny handful of extremely skilled drivers.


Nor can you take economy in isolation. If Super gives 5% more mpg, but costs 10% more, it's more expensive per mile.

As for "engine cleanliness" - all fuel comes from the same tiny handful of refineries, through the same fractionally larger handful of regional distribution depots, and is dispensed to all brands tankers. The brand-specific detergent additives are added at that point, in damn-near-homeopathic quantities. ALL fuel sold in the UK must conform to tightly defined standards. "Engine cleanliness" is mostly a snake-oil-salesman's dream. There can be inlet tract deposit issues in some engines with direct injection, but tha's because the fuel isn't passing through the inlet tract to clean any deposits (from EGR, crankcase breathing, or turbo seals) off, so the fuel used is irrelevant.

Joe_Horner

If you accidentally spill some on yourself then light a cigarette they both burn the same. Not that I'd recommend even you trying that - smoking is bad for you.

oldagetraveller

"I tend to stick with V power or BP ultimate"
That really is overkill for a Yaris. It will run quite happily on bog standard unleaded.

agrinnall

oldagetraveller wrote: »

"I tend to stick with V power or BP ultimate"
That really is overkill for a Yaris. It will run quite happily on bog standard unleaded.

I believe they actually run better on unicorn urine.

Navigator123

I use bog standard regular Sainsbury's unleaded but put a bottle of STP in the tank once every 4 months.

Driving a Hyundai i30 1.4 petrol which is 6 years old with 60,000 miles on the clock for mainly town/short trip driving and averaging 41 mpg.

pogofish

Not... This... Again....!

Car_54

pogofish wrote: »

Not... This... Again....!

It's getting better. This time we got to post #8 before someone suggested adding a bottle of snake oil every few months.

TONX_2

AdrianC wrote: »

Firstly, the vanilla 95RON is "Premium Unleaded". Look at the pump. Be VERY careful about US and European differences in terminology and the way in which octane is measured.


There are five European standards for unleaded, three of which are unchanged since the introduction in the 80s.
(Regular) is 91RON. It was never available in the UK, and has pretty much disappeared from those countries it was available in.
Premium is 95RON.
Super is 97+RON.
All are 5% ethanol, E5.

Then there's 10% ethanol, E10, 95RON - it's been available in other European countries for a decade or more, and is coming to the UK soon alongside E5 95 and E5 97+. All US unleaded has been E10 since the 70s. All new cars in Europe since 2011 must be fine on E10 95.

Finally, there's 85% ethanol, E85. Again, not available here, but popular elsewhere in Europe. You need a specifically-mapped car to use it.


As for 95/97+, it entirely depends on whether your engine can take advantage of the octane difference. Some - mostly high-performance - will. Most won't.

I'd suggest that a 4% peak power difference on something as fast as a BMW M5 - even a 20yo one - is utterly irrelevant on the road, and even on the track for all bar a very tiny handful of extremely skilled drivers.


Nor can you take economy in isolation. If Super gives 5% more mpg, but costs 10% more, it's more expensive per mile.

As for "engine cleanliness" - all fuel comes from the same tiny handful of refineries, through the same fractionally larger handful of regional distribution depots, and is dispensed to all brands tankers. The brand-specific detergent additives are added at that point, in damn-near-homeopathic quantities. ALL fuel sold in the UK must conform to tightly defined standards. "Engine cleanliness" is mostly a snake-oil-salesman's dream. There can be inlet tract deposit issues in some engines with direct injection, but tha's because the fuel isn't passing through the inlet tract to clean any deposits (from EGR, crankcase breathing, or turbo seals) off, so the fuel used is irrelevant.

Thanks for the info!