Is all petrol/gas the same?

[Pagey279]

I've searched for this topic and couldn't find anything.

My question is is all petrol the same, essentially is there any difference between brands? A few people I've spoken to are adamant that there is, others are adamant that there isn't.

In my experience I seem to get a bit more mileage out of 95 octane fuel from Texaco than I do from 95 octane fuel from Sainsburys, but because my car doesn't have an accurate MPG read out I can't tell for definite. The difference being the supermarket petrol is 5p cheaper per litre.

Perhaps supermarkets put in additives to effectively water down the petrol, or to maybe make it less potent. I don't know. Do you?


Edit: ahhhhh 🤬 it. I just stumbled across this https://www.gtplanet.net/forum/thre...ent-brands-advice-needed.288027/#post-8806819

My apologies.

 

[Tyger]

Essentially a lot of crude oil is the same if it is sourced the same way, but the various companies have refineries whereby crude oil is converted to petroleum spirit, so yes there would be some variety.

 

[Slash]

I've never noticed a difference but I wouldn't doubt there is differences based on some refineries and brands etc.

 

[White & Nerdy]

I'm not sure if the UK does that Top Tier Gas (or whatever it's called) thing, but if they do, just don't put anything in your car that isn't TT/whatever. I know here in Alaska that Tesoro (local company) makes my car run bad, but Chevron and Shell are fine, so I wouldn't doubt the same thing could happen elsewhere. Though I doubt a large supermarket chain would be guilty of selling really bad gas.

 

[Beeblebrox237]

Perhaps this will help shed some light on the subject?

 

[Moglet]

I'm not sure if the UK does that Top Tier Gas (or whatever it's called) thing, but if they do, just don't put anything in your car that isn't TT/whatever.

We have the more expensive 'performance fuels' but for the average car they won't make the blindest bit of difference.

Perhaps supermarkets put in additives to effectively water down the petrol, or to maybe make it less potent. I don't know. Do you?

Additives are, generally, a good thing, they don't 'water down' anything. Supermarket fuels don't have as many additives as the likes of Shell or Texaco but again, for the average car they will be fine. I used to run my RX-8 on Tesco Unleaded and it was more than quick and smooth enough.

 

[Slash]

I disagree about the additives. Anything I have that's carbureted gets gummed up incredibly faster if I run it with standard 87 unloaded from any pump versus ethanol/additive free 87 I can get from the local Indian reservation. Having tested this several times I tend to believe it. We bought a brand new lawnmower. A rider. Its carbureted. Within 2 weeks of owning it it wouldn't start because the carburetor was clogged with garbage from the fuel.

We switched to the ethanol/additive free stuff and have not had an issue since.

In fact its been said not to run modern fuel in anything older than 2005 in order to prevent premature wear on internal parts.

 

[Moglet]

I disagree about the additives. Anything I have that's carbureted gets gummed up incredibly faster if I run it with standard 87 unloaded from any pump versus ethanol/additive free 87 I can get from the local Indian reservation. Having tested this several times I tend to believe it. We bought a brand new lawnmower. A rider. Its carbureted. Within 2 weeks of owning it it wouldn't start because the carburetor was clogged with garbage from the fuel.

We switched to the ethanol/additive free stuff and have not had an issue since.

In fact its been said not to run modern fuel in anything older than 2005 in order to prevent premature wear on internal parts.

So basically you disagree about the additives on engines running carburettors and not injectors. Which doesn't matter a single bit to most of the drivers on the road who are driving cars with injectors. The chances are if you're running a car with a carb in 2014 you know enough about fuelling to choose the right grade for your vehicle.

 

[Clark]

From experience and talking with others I've always though our fuel (UK) is fine and you'll only really get a noticeable difference if you car is turbocharged.

 

[Adamgp]

I have noticed a difference in some brands. My Grand Prix did not like Citgo gas. Ran like crap and mpg suffered. Ran great on every other gas I put in.

My Escape performs the same no matter what I put in. 90% of the time I go to Marathon, since that is the one on my way home from work.

 

[TheCracker]

My car has a high compression ratio (11.3:1) and requires premium unleaded. It will take regular, but it retards the timing and the drop in performance and smoothness is quite noticeable. So it depends on the car.

 

[Slash]

So basically you disagree about the additives on engines running carburettors and not injectors. Which doesn't matter a single bit to most of the drivers on the road who are driving cars with injectors. The chances are if you're running a car with a carb in 2014 you know enough about fuelling to choose the right grade for your vehicle.

It's not just cars. It applies to a lot of things.

 

[Famine]

I disagree about the additives. Anything I have that's carbureted gets gummed up incredibly faster if I run it with standard 87 unloaded from any pump versus ethanol/additive free 87 I can get from the local Indian reservation.

Don't confuse "ethanol" with "fuel additives".

Ethanol is added to crap fuel to artificially improve the octane rating. The spectrum of fuel additives don't exist to increase octane ratings - though what they are designed to do is unique to each fuel manufacturer.

If you're running a carbed engine on junk fuel with ethanol to boost the octane rather than fuel that actually has that octane, I'm not surprised you're seeing crap performance and side-effects.

In fact its been said not to run modern fuel in anything older than 2005 in order to prevent premature wear on internal parts.

Yes, because ethanol is added to cheap fuels for the octane boost and ethanol corrodes fuel seals and lines. Current engines are designed with ethanol in mind - particularly due to the prevalence of bioethanol fuels like E85 - old ones aren't. Running ethanol through a carb is like feeding your dog acid - you're going to ruin it. Running ethanol through a carb and then blaming "fuel additives" when you ruin it is like blaming blue food colouring for killing your dog because you put a couple of drops of it in his acid.

From experience and talking with others I've always though our fuel (UK) is fine and you'll only really get a noticeable difference if you car is turbocharged.

That's more a 95-to-98 issue - and not really true anyway. It's more compression-based - high compression = higher octane to resist premature detonation.

This is more about Shell vs. Esso vs. BP vs. Supermarket and yes, there's a difference.

 

[Slash]

It's not the ethanol that worries me (well it does to an extent). While it doesn't help, it's all the detergents and other garbage that gets put in it.

 

[Famine]

It's not the ethanol that worries me (well it does to an extent). While it doesn't help, it's all the detergents and other garbage that gets put in it.

They put the ethanol into the trucks when they put the fuel in to take it to the gas stations. They don't put it in the pipelines upstream along with the fuel, because the ethanol eats the pipelines.

Don't run it through a carb. Period.

 

[Slash]

That's the problem. Finding ethanol free gas is incredibly hard. There's only one station that has it here, and it's not even that good.

 

[MatskiMonk]

From experience and talking with others I've always though our fuel (UK) is fine and you'll only really get a noticeable difference if you car is turbocharged.

I have to say, I noticed a benefit in running my E36 328i on Super, it wasn't much (and obviously I can't quantify it), but it simply felt 'meatier' through the entire rev range. I'd always use it when taking the car on 12-car Nav Rallies, where it would be driven flat-out for two hours. I'm pretty sure long-term it wouldn't be the cheapest performance upgrade for that level of performance though.

I ran my E34 525i on LPG, and there are definitely differences there! I remember stopping at some poxy little service station on the way to Croft, and gassing up from their tank - for all the good it did, I may as well have just farted into the filler valve. My local Shell stuff was much better.

 

[Moglet]

This is more about Shell vs. Esso vs. BP vs. Supermarket and yes, there's a difference.

Especially if they do what they did at one of the supermarket stations down here and get sand/grit in the fuel. That was one to avoid for a few months.

 

[White & Nerdy]

In fact its been said not to run modern fuel in anything older than 2005 in order to prevent premature wear on internal parts.

Well that's just great. Where am I gonna get old gas specifically for my 1993 car?

Ethanol is added to crap fuel to artificially improve the octane rating. The spectrum of fuel additives don't exist to increase octane ratings - though what they are designed to do is unique to each fuel manufacturer.

That might explain why the Sunbird runs so much worse on Tesoro's cheaper gasoline, even though it's injected.

I use Chevron when I can get it, though Shell will do in a pinch. I've never noticed any difference in performance between the two, though on such a low-tuned engine I doubt I would.

 

[Slash]

Especially if they do what they did at one of the supermarket stations down here and get sand/grit in the fuel. That was one to avoid for a few months.

I avoid any station that's filling up their tanks. It stirs up the crap on the bottom.

 

[Danoff]

Perhaps this will help shed some light on the subject?

If RON is equivalent to US Octane, the crap fuel they tested is our equivalent of premium. My understanding is that the Golf GTI tested requires 91 or more octane. They tested 95 and 97? That's not going to make a difference.

Here in the US, regular unleaded is 87 octane. I would expect to see a significant HP drop and worse mileage.

Edit:

Ok someone online (so they can't be wrong) said RON x 0.95 is roughly US octane. I think it's more complicated than that, but it still looks like all of the fuel tested is "premium" in the US.

 

[Joey D]

Little farm towns are probably going to be the easiest place to find ethanol free fuel. I only buy it for my yard equipment since that's what recommended for it, but for my car I've never been able to find it in the correct octane rating since it's all 91 and the owners manual on my car says it needs 93. I'm sure it would run just fine though.

 

[Beeblebrox237]

If RON is equivalent to US Octane, the crap fuel they tested is our equivalent of premium. My understanding is that the Golf GTI tested requires 91 or more octane. They tested 95 and 97? That's not going to make a difference.

Here in the US, regular unleaded is 87 octane. I would expect to see a significant HP drop and worse mileage.

Edit:

Ok someone online (so they can't be wrong) said RON x 0.95 is roughly US octane. I think it's more complicated than that, but it still looks like all of the fuel tested is "premium" in the US.

Yeah, fuel in Europe is as standard a slightly higher octane, which is why so many European cars sold in America require premium fuel.

 

[TheCracker]

US and European octane ratings are calculated differently. Regular and premium fuels are near enough the same thing in either continent, with some slight regional differences.

 

[Famine]

If RON is equivalent to US Octane, the crap fuel they tested is our equivalent of premium. My understanding is that the Golf GTI tested requires 91 or more octane. They tested 95 and 97? That's not going to make a difference.

Here in the US, regular unleaded is 87 octane. I would expect to see a significant HP drop and worse mileage.

Edit:

Ok someone online (so they can't be wrong) said RON x 0.95 is roughly US octane. I think it's more complicated than that, but it still looks like all of the fuel tested is "premium" in the US.

It is both about right and a little more complicated than that.

"Octane" is the average of two numbers: RON and MON. RON is typically 8-10pt higher than MON and so the average is usually 4-5pt lower than RON.

It gets a little more complex because you could in theory have a RON fuel at 97 but with an Octane rating of 49, because the MON rating is 1. In practice we have minimum standards of MON as part of the certification process of fuels to certain RON ratings.

Octane is, in theory, a better rating as MON is more appropriate to real world conditions than RON and it's not unwise to have that number included. In practice it doesn't make a whole lot of difference.

87 Octane = 91 RON
91 Octane = 95 RON
93 Octane = 98 RON

Job jobbed.

 

[Danoff]

It is both about right and a little more complicated than that.

"Octane" is the average of two numbers: RON and MON. RON is typically 8-10pt higher than MON and so the average is usually 4-5pt lower than RON.

It gets a little more complex because you could in theory have a RON fuel at 97 but with an Octane rating of 49, because the MON rating is 1. In practice we have minimum standards of MON as part of the certification process of fuels to certain RON ratings.

Octane is, in theory, a better rating as MON is more appropriate to real world conditions than RON and it's not unwise to have that number included. In practice it doesn't make a whole lot of difference.

87 Octane = 91 RON
91 Octane = 95 RON
93 Octane = 98 RON

Job jobbed.

Thanks for that. So as I suspected, our premium gasoline is your 95 RON. 93 Octane is a bit less common here and doesn't exist in all areas. So I'm not surprised that there is no difference in performance above 91 Octane. It seems most cars that are designed to require 91 Octane don't take advantage of any more than that.

I'll also note that a lot of the advice on the interwebs is that you should increase your Octane until your car stops knocking. I find that a bit outdated since modern cars adjust timing to the Octane level and will just give you worse gas mileage and lower horsepower without making any noise in the process.

 

[niky]

It's not the ethanol that worries me (well it does to an extent). While it doesn't help, it's all the detergents and other garbage that gets put in it.

It's been explained, but it's worthwhile to note that these are common issues with carbureted engines and old two-stroke lawn machinery... and problems are always traced to the ethanol, not the additives.

 

[Mikeybc]

Just peeked into this thread, I've never gave gasoline too much thought the last few years, but will now be seeking a source for ethanol free gas for my small engine/powersport stuff.

I found a useful site that tracks non ethanol gasoline stations in North America...not sure how up to date it is. Just click the state or province you're in at the bottom.

http://pure-gas.org/index.jsp

 

[JMoney]

Wish I could have 95 Octane here, the highest I've seen is 93.

 

[Slash]

Local truck stop or airport should have it.