Fuel additives

Mercdriver

Tesco in my area are usually the most expensive.  They do do a local check on prices - when someone else puts up their price to match them, Tesco puts theirs up by a penny

[Deleted User]

Snake oil or not they can/do help keep your car run clean and smoother. It's not all about getting loads of extra MPG what everyone only seems to think about when ever additives are mentioned.

AdrianC

Deleted_User said:

Snake oil or not they can/do help keep your car run clean and smoother. It's not all about getting loads of extra MPG what everyone only seems to think about when ever additives are mentioned.

Probably because that's how they're marketed. And if they fail in their primary marketed purpose...

How many cars die because the fuel system is clagged up?

Goudy

It's true that higher octane fuels ignite quicker than lower octane fuels.

So it's a fact in a engine that fires many times a second, the earlier it ignites, the more time it has to complete burning, so you get a better, completer burn which leads to slightly more power and less leftover in the chambers which tends to turn to carbon deposits.

Most modern cars can cope with this and alter their ignition to handle it to a certain extent.

Knock sensors on the engine monitor the engine "pinging" or pre ignition and if it can it will adjust the spark timing to cope better with how soon the fuel ignites.

Some cars are better than others at this as it's all done to the perimeters set within the engines ECU, which is why some adjust these setting themselves with a remap.

The same goes for diesel, though it's cetane rating for this, diesel ignites under pressure without a spark, so the higher the cetane rating the sooner it will auto ignite, this means it will self combust slightly sooner under slightly less pressure than lower rated cetane fuel. The results of this are similar as above, the sooner it ignites, the more time it has to completely it's burn, so you get more out of each bang.

Again, the better the engines ECU can detect and adjust the bang which is does with injection timing (no spark in a diesel engine) the better it can use the fuel.

So what fuel companies tell you about higher octane fuels is true as the fact they burn quicker and more completely in a cycle can result in more power, better mpg and less carbon, how much depends on how your car can handle it and if the extra's out weigh the cost.

As for cleaning additives, there's been little work done to see if they do have major benefits.

A German manufacturer did some work a few years ago with diesel fuel additives. The results were quite interesting and are floating about the internet.

Most have some cetane booster (2 EHN) in them, though the levels weren't always enough to treat more than a few litres adequately and they all had various levels of lubricant in them and most had solvents to help breakdown the fuels surface tension, again levels weren't really adequate.

It turned out ml for ml, pound for pound,  adding a small shot of 2 stroke engine oil resulted in lowering the fuels auto ignition point more and lubricated the mechanical parts better than all the commercial products and as it produces less soot and ash then the carrying diesel, there's nothing detrimental in the exhaust that effects emissions or DPFs.

Goudy

Goudy said:

As for cleaning additives, there's been little work done to see if they do have major benefits.

A German manufacturer did some work a few years ago with diesel fuel additives. The results were quite interesting and are floating about the internet.

Most have some cetane booster in them, though the levels weren't always enough to treat more than a few litres adequately and they all had various levels of lubricant in them and most had solvents to help breakdown the fuels surface tension, again levels weren't really adequate.

It turned out ml for ml, pound for pound,  adding a small shot of 2 stroke engine oil resulted in lowering the fuels auto ignition point more and lubricated the mechanical parts better than all the commercial products and as it produces less soot and ash then the carrying diesel, there's nothing detrimental in the exhaust that effects emissions or DPFs.

I'm not suggesting anyone does this BTW, it's just what was found in their tests.

red_eye

Goudy said:

It's true that higher octane fuels ignite quicker than lower octane fuels.

So it's a fact in a engine that fires many times a second, the earlier it ignites, the more time it has to complete burning, so you get a better, completer burn which leads to slightly more power and less leftover in the chambers which tends to turn to carbon deposits.

Most modern cars can cope with this and alter their ignition to handle it to a certain extent.

Knock sensors on the engine monitor the engine "pinging" or pre ignition and if it can it will adjust the spark timing to cope better with how soon the fuel ignites.

Some cars are better than others at this as it's all done to the perimeters set within the engines ECU, which is why some adjust these setting themselves with a remap.

The same goes for diesel, though it's cetane rating for this, diesel ignites under pressure without a spark, so the higher the cetane rating the sooner it will auto ignite, this means it will self combust slightly sooner under slightly less pressure than lower rated cetane fuel. The results of this are similar as above, the sooner it ignites, the more time it has to completely it's burn, so you get more out of each bang.

Again, the better the engines ECU can detect and adjust the bang which is does with injection timing (no spark in a diesel engine) the better it can use the fuel.

So what fuel companies tell you about higher octane fuels is true as the fact they burn quicker and more completely in a cycle can result in more power, better mpg and less carbon, how much depends on how your car can handle it and if the extra's out weigh the cost.

As for cleaning additives, there's been little work done to see if they do have major benefits.

A German manufacturer did some work a few years ago with diesel fuel additives. The results were quite interesting and are floating about the internet.

Most have some cetane booster (2 EHN) in them, though the levels weren't always enough to treat more than a few litres adequately and they all had various levels of lubricant in them and most had solvents to help breakdown the fuels surface tension, again levels weren't really adequate.

It turned out ml for ml, pound for pound,  adding a small shot of 2 stroke engine oil resulted in lowering the fuels auto ignition point more and lubricated the mechanical parts better than all the commercial products and as it produces less soot and ash then the carrying diesel, there's nothing detrimental in the exhaust that effects emissions or DPFs.

Octane is the ability to resist pre ignition/knock.
 If you skim your head to increase the compression ratio the cylinder temp will go up and so will the risk of fuel igniting by heat and not the spark. This is where you would use a high octane fuel and use the extra power gains from the high c/r, or let the ecu adjust for 95 and lose the gains.

fuel igniting at the wrong time can turn your engine into a frag grenade  

AdrianC

Goudy said:

It's true that higher octane fuels ignite quicker than lower octane fuels.

So it's a fact in a engine that fires many times a second, the earlier it ignites, the more time it has to complete burning

Nope. It's the complete opposite.

Octane is the fuel's resistance to premature ignition - pinking.

Higher octane fuels are more reluctant to ignite, which means they can be used at higher compression ratios or higher turbo boost, which is what gives the extra power.