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Old 11th June 2019, 14:19   #41
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Originally Posted by bl52krz View Post
My car failed the mot on emissions this year,March. Just to concentrate on diesel, I was advised to change my engine oil to a C3 derivative to help with emissions.I was also advised to use the ‘better quality’ diesel fuel for the re-test. I filled up with C3 oil as suggested, and also put around 10 gallons of BP ‘best quality’ diesel in the tank.
I cleaned the egr out. Not much gunk in it. My car passed the mot test. I continued using BPs finest for the next two fill ups. My conclusions were:- Same mpg. The engine did seem to pick up revs easier. The last two fill ups were from Asda, the terrible junk diesel.The mpg was the same. It picked up revs just as easy as when on BPs super duper diesel. My only conclusion from this is:- that the Magnatec C3 fully synthetic 5w40 oil was what made the difference in the faster pick up. It is also recommended for the diesel in place of 10w40. It achieved the same test results as the 10w40..

Could it also be that the premium fuel cleaned the injectors etc. and this is benefiting the follow-on refills with non-premium fuel?
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Old 11th June 2019, 14:40   #42
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Originally Posted by bl52krz View Post
My car failed the mot on emissions this year,March. Just to concentrate on diesel, I was advised to change my engine oil to a C3 derivative to help with emissions.I was also advised to use the ‘better quality’ diesel fuel for the re-test. I filled up with C3 oil as suggested, and also put around 10 gallons of BP ‘best quality’ diesel in the tank.
I cleaned the egr out. Not much gunk in it. My car passed the mot test. I continued using BPs finest for the next two fill ups. My conclusions were:- Same mpg. The engine did seem to pick up revs easier. The last two fill ups were from Asda, the terrible junk diesel.The mpg was the same. It picked up revs just as easy as when on BPs super duper diesel. My only conclusion from this is:- that the Magnatec C3 fully synthetic 5w40 oil was what made the difference in the faster pick up. It is also recommended for the diesel in place of 10w40. It achieved the same test results as the 10w40..
I wonder if cleaning the egr help too? It is an emissions control device after all.

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Old 11th June 2019, 16:12   #43
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Originally Posted by marinabrian View Post
All of the petrol variants of our cars are tuned in the UK to use 95 Ron fuel, there is absolutely no benefit whatsoever in using 98 Ron fuel, the car will not run better, you will not become irresistible to the opposite sex, and your car will not do an extra 50 MPG.

Higher octane fuel is less prone to pinking............so if you need to fuel your P6 V8 with five star, then you can still buy "real" petrol from BMH.



Back to the here and now, other markets are tuned for lower Octane fuels, Australia for instance use 92 RON fuel, and their "premium" fuel is actually 95 RON

With the low mileage cars, I leave only a small amount of fuel in there, and when pressed into action, fill as required as modern fuels tend to go stale when standing, due to the ethanol content as required by the EU,being both hygroscopic and having a tendency to evaporate off, this of course applies to both 95 and 98 RON fuel.

Another fact, the higher the octane rating, the higher the temperature of the spark required to ignite the mixture, this is why the ignition system of cars running LPG need to be in top condition.......incidentally LPG is circa 110 RON, however the calorific value is lower than petrol, so you have to burn 20% more to achieve the same output.

It's not all about octane either, a little light reading HERE

Brian
Best give Esso Petroleum a bell then, Brian, and tell them that their Technical Data Sheet is wrong, as is their FAQ on their website.

https://www.esso.co.uk/fuels-faqs
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Old 11th June 2019, 19:33   #44
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Hi Alan. There was next to nothing in the egr. Took about five minutes to wipe it out.I always use Redex so there could not have been any fouling of the injectors. I honestly think it is the lower 5w40 oil.
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Old 11th June 2019, 19:59   #45
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Hi Alan. There was next to nothing in the egr. Took about five minutes to wipe it out.I always use Redex so there could not have been any fouling of the injectors. I honestly think it is the lower 5w40 oil.
I am not saying it isnt, although I would imagine it would take more than one oil change (on what I assume to be a regularly serviced engine - an oil or PCV filter change may do it too) , and a fill of fuel to do it. I can see the potential in the fuel having a little improvement once it had got well through the system - though I am not convinced.

If the EGR was sticking, and you used fluid to clean or even nudging the actuator to wipe may have loosened it up to work. Removing the vacuum pipe and refitting even could have got it going again.

I have to say though, at present and for the past 12 or 13 years we dont have emissions tests on the diesels, after they were abandoned due to concerns of engine failures. :eek :

The 5w40 part of the oil wont be the benefit, but the ACEA rating as this relates to ash(?) content or something - even the oil change itself could possibly be the issue? The Redex, may well maintain the fuel system, again I whilst I do not know, I think with modern fuels and tolerances etc it is less benefit than it would have been 30/40 years ago. It showed absolutely no benefit to me when I compared injector readings on an overnight soak with redex compared to an overnight soak the following week with Forte (they are very different products though!). I do believe Redex to be unnecessary in this day and age. Like a dying atheist, converting to christianity, I still buy it when on offer and add it when I remember . But the injectors will still wear down over time (affecting spray pattern, volume etc).

There are simply too many variables for me to suggest that it was the fuel.
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Old 11th June 2019, 20:29   #46
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Did you know that you can get more or less feeling of power depending on the material your trousers are made from ???

Most of the guys on this thread use the seat of their pants as a finely tuned instrument to make their judgements.

So guys, try silk pants on leather seats to give yourselves the thrill of your lives.----

Go on; you know it makes sense.--

At least as much sense as this thread.--
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Old 11th June 2019, 20:36   #47
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Originally Posted by roverbarmy View Post
The only proven way to get more mpg from your car is an industry secret .................................
Move your seat back a notch! Moving it forwards gives you more power, less MPG and cramp on long journeys (unless using cruise control, which is being debated elsewhere!).
Brilliant. So good in fact I shall go out of my way to give you your 1,000th thanks.---
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Old 11th June 2019, 20:46   #48
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Quote:
Originally Posted by marinabrian View Post
All of the petrol variants of our cars are tuned in the UK to use 95 Ron fuel, there is absolutely no benefit whatsoever in using 98 Ron fuel, the car will not run better, you will not become irresistible to the opposite sex, and your car will not do an extra 50 MPG.

Higher octane fuel is less prone to pinking............so if you need to fuel your P6 V8 with five star, then you can still buy "real" petrol from BMH.



Back to the here and now, other markets are tuned for lower Octane fuels, Australia for instance use 92 RON fuel, and their "premium" fuel is actually 95 RON

With the low mileage cars, I leave only a small amount of fuel in there, and when pressed into action, fill as required as modern fuels tend to go stale when standing, due to the ethanol content as required by the EU,being both hygroscopic and having a tendency to evaporate off, this of course applies to both 95 and 98 RON fuel.

Another fact, the higher the octane rating, the higher the temperature of the spark required to ignite the mixture, this is why the ignition system of cars running LPG need to be in top condition.......incidentally LPG is circa 110 RON, however the calorific value is lower than petrol, so you have to burn 20% more to achieve the same output.

It's not all about octane either, a little light reading HERE

Brian
Yer.---



Now for the chemistry lesson: Oil is a hydrocarbon fuel, meaning the individual molecules contain carbon and hydrogen atoms chained together. Modern petrol is blended according to various recipes, the active ingredients for which include about 200 different hydrocarbons, each with a spine of between 4 and 12 carbon atoms. One of them, isooctane, consists of 8 carbon and 18 hydrogen atoms (C8H18) and is exceptionally resistant to exploding spontaneously when exposed to the heat and pressure found inside a typical combustion chamber. Another, n-heptane (C7H16) is highly susceptible to such self-ignition.

These two compounds are therefore used to rate the knock resistance of all petrol blends. Petrol that resists knock the way a mixture of 87-percent isooctane and 13-percent n-heptane would is rated at 87. Racing fuels with octane ratings over 100 resist self-ignition even better than pure isooctane. The octane ratings for regular-grade fuel range from 85 to 87, mid grades are rated 88 to 90, and 91 and higher is premium.
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Old 11th June 2019, 20:56   #49
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Originally Posted by COLVERT View Post
Brilliant. So good in fact I shall go out of my way to give you your 1,000th thanks.---
Its a bit like, how long is a piece of string?. All I can say is I have used Redex and as far as I know, it has not done my engine any harm, main thing. Snake oil might do the same thing, but I don’t know where to get any. Another thing, you can save petrol or diesel if you force a potato up your exhaust pipe on your car. Try it, I found out years ago that it does work. I won’t tell you how though.
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Old 12th June 2019, 06:39   #50
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Quote:
Originally Posted by COLVERT View Post
Did you know that you can get more or less feeling of power depending on the material your trousers are made from ???

Most of the guys on this thread use the seat of their pants as a finely tuned instrument to make their judgements.

So guys, try silk pants on leather seats to give yourselves the thrill of your lives.----

Go on; you know it makes sense.--

At least as much sense as this thread.--

Quote:
Originally Posted by COLVERT View Post
Yer.---

Now for the chemistry lesson: Oil is a hydrocarbon fuel, meaning the individual molecules contain carbon and hydrogen atoms chained together. Modern petrol is blended according to various recipes, the active ingredients for which include about 200 different hydrocarbons, each with a spine of between 4 and 12 carbon atoms. One of them, isooctane, consists of 8 carbon and 18 hydrogen atoms (C8H18) and is exceptionally resistant to exploding spontaneously when exposed to the heat and pressure found inside a typical combustion chamber. Another, n-heptane (C7H16) is highly susceptible to such self-ignition.

These two compounds are therefore used to rate the knock resistance of all petrol blends. Petrol that resists knock the way a mixture of 87-percent isooctane and 13-percent n-heptane would is rated at 87. Racing fuels with octane ratings over 100 resist self-ignition even better than pure isooctane. The octane ratings for regular-grade fuel range from 85 to 87, mid grades are rated 88 to 90, and 91 and higher is premium.

None of what you or Marinabrian says means that a car that is tuned (i.e. optimised) to run with a certain RON or Cetane fuel will not benefit from a higher rated fuel. The reason is that there are always multiple variables under consideration when optimising any thermal or physical process.

You need to do some real-world tests instead of trying to baffle members with atomic structures of hydrocarbons.

It appears that some members may speak with their trousers full
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