Regular & Premium Petrol comparison

[g8dhe]

Recently I had the opportunity to make two similar long trips the length of the country so I decided to make extra use of the journeys to make a comparison of the fuel types in my V6.
Before starting the the Premium fuel session, I allowed a full one and a half tanks to be used to ensure that the tank was only premium and that the engine had been working on it before the actual measurements.

First the trips:
Yellow was the Regular petrol, in August including the Bongo Bash mini-meet at Dent. I was carrying extra weight (5 tyres) Worthing to Dent.
Red was the Premium petrol, last week when I was providing cover and support for the Great Glen Ultra SuP Challenge for Phil my son. I was carrying a 14' SuP board on the roofrack to and fro.

Click the images below for a full size image.



Below is the table from my ongoing spreadsheet for fuel comparison, again click for a readable size!



The two coloured areas on the righthand side compare the two trips, below is the same info;
Regular Petrol
23.69 mpg
1491 miles
£322.72 cost
£0.22 £pm

Premium Petrol
23.07 mpg
1598 miles
£374.60 cost
£0.23 £pm

So not a lot in it in terms of cost or performance between the two, neither of us whilst driving could identify any difference in power levels or performance between the two fuels either.

[Bob]

Most interesting, and well done keeping such thorough records.

[mikeonb4c]

Very interesting Geoff and you are left to wonder what the difference is. I suppose there's a possible long term benefit of one over the other but it might be even harder to establish!

[g8dhe]

Yup there is supposed to be less wear I believe, but not something I can measure - and I doubt that many well funded organisations could do either!
I had hoped for a clear difference, so will continue the trial with and without the SuP board on the rack to see if that has a significant effect, quite likely I suspect!

[Jimbobvfr400]

Very interesting Geoff and you are left to wonder what the difference is. I suppose there's a possible long term benefit of one over the other but it might be even harder to establish!

You'd soon notice the difference if you ran a performance car designed to use higher octane fuel. My mate had a Subaru that was supposed to use 98RON fuel. It would run on 95 but the ECU would retard the ignition to prevent knocking or pinking and it would be noticeably less powerful.
On more normal cars I've not been able to tell the difference between regular and super unleaded. I'ts simply not needed IMO

[JoeC]

One thing I have always wanted to know the answer to ... is it better to use 'premium' supermarket fuel or just standard branded fuel?
Same sort of thing that you are looking into here.

[the1andonly]

Very interesting Geoff and you are left to wonder what the difference is. I suppose there's a possible long term benefit of one over the other but it might be even harder to establish!

You'd soon notice the difference if you ran a performance car designed to use higher octane fuel. My mate had a Subaru that was supposed to use 98RON fuel. It would run on 95 but the ECU would retard the ignition to prevent knocking or pinking and it would be noticeably less powerful.
On more normal cars I've not been able to tell the difference between regular and super unleaded. I'ts simply not needed IMO

i'TS all about what the engine was designed to use, todays petrol is not the same as in 99, differemt blends including ethanol which then brings in a new bag of spanners to wreak engines and other additives needed for engine wear aspects. The interesting question (JoeC) are supermarket fuels just reaching the specs and premium fuels or additives required which is the most cost effective. (ps i'm not a fuel chemist)
Was the V6 ever used with 4star (no cat version?)
For the wrinklies out there remember 5 star and fuel supply problems of the 70's. I even remember mixing 2 and 5 star in the tank as there was no 4 star about.

[Glenda]

Good test, Geoff. Out of interest what was your average motorway speed? The test gives a good mpg for the V6.

[g8dhe]

Hah depends which bit of motorway Mainly aim for high 60's but often up in the 70's apart from the bottom end of the M6 which is more like 40's in the road works! The A9 is virtually all Average speed 50mph.

MPG by distance below, click for fullsize;

[Glenda]

I wasn't expecting such a detailed answer. Excellent chart. Thanks.

[BongoBongo123]

Nice stats Geoff and seem like any differences could have been down to wind resistance on the days alone.

To sound somewhat like a broken record I use Millers in both my petrol and diesel and can hear and feel the difference
in sound of both engines when it is absent. I suspect this quietening is down to reduced valve friction.

Using Millers is, I suspect somewhat similar to using premium fuel except it is about 15pct of the cost of filling up with premium petrol/diesel.

I quote myself from another thread on this sub forum:

"The difference for 10 tanks of supreme diesel would be £84.50 vs £13.00 for a bottle of millers."

I also imagine that premium fuel or Millers would reduce accumulative carbon build up on top of pistons and valves/combustion chambers, keeps injectors spray pattern as good as new.. and so you may see reduced performance over a longer period if using normal petrol/diesel alone.

(In fact I got a bottle of Millers Petrol Eco max this morning for £12.99 in Halfords) This low price coupled with an audible and sensed improvement (smoother) makes me feel it is very worthwhile. I have no info regarding economy and suspect it would be little to no difference but if it protects the engine and makes it more pleasant to drive it's a winner for me. (I also hope it reduces pollutants a little by keeping the combustion as economical and efficient as possible)

[Markas]

To sound somewhat like a broken record I use Millers in both my petrol and diesel and can hear and feel the difference
in sound of both engines when it is absent. I suspect this quietening is down to reduced valve friction.

Using Millers is, I suspect somewhat similar to using premium fuel except it is about 15pct of the cost of filling up with premium petrol/diesel.

I'm not familiar with this additive; what are its claimed benefits? I do use a Millers octane boosting additive in one of my Dolomites, a 1500, which is run on supermarket 99RON. The additive also claims to prevent valve-seat recession.
My other Dolly, an 1850, has a 'modern' alloy head so that gets the same fuel but without an additive, again because the original fuel specified was 4*. With a relatively modern vehicle like a Bongo I use bog-standard supermarket 'normal' petrol. Even my daily driver Merc takes the same stuff.

[BongoBongo123]

2 point octane/cetane bost per 50 mL dose, improved economy, power, lubrication/cleaning injectors, reduced pollution (hydrocarbons) is claimed.

[frogeyepete]

Kind of makes you wonder if regular and premium come out of the same tank! Certainly different brands if petrol come from the same depot. I did hear once however that the Shell tanker drivers carried a plastic container of magic liquid to add to the petrol to make theirs a bit special. Sounds a bit like homeopathy to me.

[BongoBongo123]

2 bottles of redex