Diesel additives – worth it?

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  • Diesel additives – worth it?
  • Premier Icon Johnny Panic
    Subscriber

    The ones for cleaning out the injectors?

    Premier Icon jam bo
    Subscriber

    Surely the car manufacturers would recommend them if they were…

    schrickvr6
    Member

    Not so much for cleaning the injectors but raising the cetane rating I use Millers which is widely regarded as the best of it’s kind.

    Premier Icon Johnny Panic
    Subscriber

    Do you notice any difference in oomph or mpg?

    swamp_boy
    Member

    Used Millers regularly in my last car [Land rover 300tdi]. No noticeable change in oomph, but always ran nice and clean, never had injector problems and sailed through MoT emission tests right up until I sold it with 228,000 miles on the clock. But I also serviced it regularly. And avoided supermarket fuel.

    Premier Icon scaredypants
    Subscriber

    I’d have thought that the “magic” of those additives would be that you can use supermarket fuel ?

    Premier Icon Johnny Panic
    Subscriber

    Um, I usually use supermarket fuel. It’s no different really is it? That’s another forum topic I think 🙂

    Back to additives, in halfrauds there were at least three different redex additives for diesel. Different prices, one bottle was add it all to an empty tank, another was add an eigth to each tank full. Confusing.

    konabunny
    Member

    Would also be curious about the worthwhileness 😉 of these, and the injector/carby cleaner things that come in the same bottles.

    globalti
    Member

    Just take it for a long fast drive down the motorway. Mrs Gti has a C1 diesel, which until recently was only getting used for the school run and it ran badly, jerky and juddery and not very nippy. Then she got an area sales job and is now driving it all around NW England and the transformation is unbelievable; it goes like a little rocket and is as smooth as silk.

    On the odd occassion I’ve used supermarket fuel in my pick-up, it has run like a tractor and returned poor mpg.

    Premier Icon andydicko
    Subscriber

    If the car you’re putting it in is non DPF (diesel particulate filter) then yes get the stuff used, wouldn’t reccommend in DPF cars though as the additives are oil based and when oil is burn’t it produces ash, which blocks DPF’s

    Erm, diesel is oil based….

    schrickvr6
    Member

    I use the Millers with supermarket fuel in my fabia just to be on the safe side as it’s pretty highly tuned for a diesel.

    Premier Icon chainslapp
    Subscriber

    The only way to properly clean fuel injectors, is to have them removed and serviced by someone who knows what they are doing IMO. The cleaner additives increase either the octane or cetane levels within the fuel and make it feel like something has taken place with the cleaning of the injectors.

    b r
    Member

    The injectors in my wife’s went for a second time, the garage reckoned it was due to her using supermarket/no-name fuel. She now doesn’t plus often puts through a tank of ‘super’ diesel.

    Seems to both run better and does do more mpg.

    Premier Icon andydicko
    Subscriber

    TheArtistFormerlyKnownAsSTR – Member
    Erm, diesel is oil based….

    Very true, but when a DPF and the management system are designed and are working together, they are designed with Diesel in mind, not OIL, any additional oil’s aren’t taken into account with the life of a DPF, so if you use additives, or even cooking oil you’ll drastically reduce the life of a DPF

    bigbloke
    Member

    I second the supermarket fuel thing. On several trials as i am a sceptic about things unless i try them i have filled up at my local place which is a supermarket and the car ran louder and more “clattery” (diesel) plus the mpg did go down a little. I always now try and use main brand garages, it does make a difference if only a little.

    craigxxl
    Member

    Try some BG244. It sorted the rough startups I had with my diesel Mondeo. I had previously tried Millers and Forte without success. I will be using it as part of it’s annual service from now on.
    The father-in-law tried it on his cars and noticed a smoother and quieter engine on the Saab 93 but reckons the VW Polo felt much better even though it didn’t have any problem before and was less than 2 year old.

    You get BG244 from Ebay or direct from Powerenhancer.

    Premier Icon scaredypants
    Subscriber

    slightly off-topic

    my petrol car failed its MoT on emissions. Tried a few measures, like ragging the arse off it and a tankful of “normal” aditive (stp maybe) but no effect

    a bottle of cataclean, 10 miles on the motorway later and easy pass

    (the stuff is FANTASTIC for sniffin’ too)

    Premier Icon Rusty Spanner
    Subscriber

    Redex is basically paraffin.

    Availlable much cheaper elsewhere.

    nasher
    Member

    I did a thousand mile journey to italy and after using a tank of fuel, i added some wynns cetane booster, cleaner thingy…. adfter doing 400 miles in a tank with out and immediately again with the additive I noticed a difference, performance was better and I got an extra 40 miles before the next fill up..

    The car was big heavy 16 year old 4*4 with and old 2.8 TD engine..

    Premier Icon molgrips
    Subscriber

    Right.

    Most of these additives contain something called 2-EHN which is a cetane booster. And most of them dilute it with paraffin. It’s the same stuff that you get in ‘super’ diesel, and it does definitely raise the cetane number of your fuel. This (unlike higher octane petrol) will improve starting, smooth running, performance and economy to varying degrees. The smooth running is obvious, the economy and performance less so but I have still noticed 1-2mpg I reckon.

    Now – super diesel (ie BP Ultimate) works the same as using the additive, but the additives are usually cheaper. If you buy 2-EHN in buulk from ebay or elsewhere online it’s way cheaper and not diluted either.

    I’m less sure as to whether or not it cleans injectors. My local servicing place uses something much more expensive, like £20 a treatment, because they say it works rather than Redex which doens’t work very well.

    The Italian method works well too (ie ragging it, the longer and faster the better).

    EDIT: Might be BG244 that the garage recommended, actually.

    Big Dave
    Member

    The Italian method works well too (ie ragging it, the longer and faster the better).

    Certainly seems to be the right approach if you have a Fiat. My dad’s Panda has been running quite rough recently. I’ve found that driving it like an Italian; bouncing off the rev limiter with every gear change and going everywhere flat out, has left it running much more smoothly and has improved the fuel efficiency 😯

    mc
    Member

    The smoother running will be more aparent on older diesels, as modern diesels adapt to slight variations in fuel.

    By raising the cetane level, you’re making the fuel easier to burn, which is why it helps with starting and smooth running. Adding some petrol also has a similar effect, but can cause fuel system lubrication issues (although not as many as the removal of sulphur caused!)

    boltonjon
    Member

    Unfortunately, fuel additives will provide no benefits

    During my automotive engineering degree, i performed an analysis on a engine on a test bed. I used 3 different additives and standard fuel. Running the exact same test, there was no difference in power, torque or fuel economy.

    I was unable to test if the engine was quicker to pick up though.

    The best way to keep a diesel engine running sweetly is to change the air & fuel filter regularly, use quality fuel and give it a good thrashing every so often, to blow the soot out of the system.

    craigxxl
    Member

    So did your test bed engine have dirty injectors and build up in the fuel system?

    Pieface
    Member

    Makes no difference to my petrol engine, always runs really smoothly and quietly.

    I tried the Miller Eco Max in my picasso diesel on a 400 mile trip across france
    As it says on the bottle you will notice a differance after 200 miles and yes after about 200 miles the engine was ALOT quieter and smoother
    I find it also gives me about 4mpg fuel increase for £1.20 a tank
    My wife also finds her 306 petrol runs alot better for the miller petrol additive

    Premier Icon Woody
    Subscriber

    boltonjon

    What additives did you test and on what sort of engine?

    Not trying to catch you out, just genuinely interested as I tried a can of Ametech engine restorer in my car (petrol) a couple of months ago. I’ve done about 1500 miles in that period and the engine seems quieter/smoother and mpg has improved by 1-1.5mpg.

    Not very scientific admittedly but there are an awful lot of ‘satisfied customers’ reporting the same or better results. They can’t all be Ametech employees can they……or can they ❓

    Suggsey
    Member

    I too recommend the Millers or use 1 tank in every four of posh diesel and never use supermarket diesel or my cheap local petrol station fuel as it makes the car run noticeably poorly 178k VW Passat Tdi thats driven hard daily. (I also run a magnetic pre burn catalyst too for a cleaner more total diesel burn)

    Pieface
    Member

    This is why I hate diesel cars, you become obsessed with fuel economy. At least with a petrol you know you’re getting poor MPG so just get on with it.

    FWIW I tried Miller’s / Redex / others, special diesel, supermarket diesel… didn’t make a blind bit of difference.

    boltonjon
    Member

    Hi Woody

    Please bear in mind that my project took place back in the late 90s during a very drunken part of my life!!

    The engine was some sort of Cummings engine, probably similar to an engine you might find in an old LDV or land rover – 70s technology i’d guess, but even with all the latest fancy diesel technology, the concept is still the same

    I think we tried some Wynns additive and maybe some Redline or something. We picked the 3 top sellers at the time

    I’m impressed that you can notice an increase of 1.5% in your fuel economy though!! 😀

    I don’t travel a huge distance so have never been to worried about fuel economy, but i’ve recently acquired an old Audi A4 with an LPG conversion

    I am proper impressed. 68p a litre. its like buying fuel in 1993

    The engine is a 2.6 V6, but with the low cost, its the equivalent of getting about 50mpg and it goes like stink.

    Premier Icon Woody
    Subscriber

    It’s 1 – 1.5 mpg more on usual weekly commute. Average before was 31 now getting 32-33 mpg and 40 on a long run as opposed to 37, so overall 5% + improvement in economy. I’m not doing high mileage but it saves me about £7 a month so will pay for itself in a couple of months

    TBH I’m more impressed with how much smoother and quieter the engine is and like most people I was VERY sceptical before I tried it. It’s the first additive I’ve tried out of injector cleaners, Slick50, octane boosters etc. etc. that has actually made a noticeable difference.

    konabunny
    Member

    I also run a magnetic pre burn catalyst

    I know nothing about the science but aren’t those things that are sold on eBay and regarded as snake oil?

    chewkw
    Member

    Not sure about additive but my friend usually put some 2T motorbike oil into the diesel oil mix. About 100ml to 200ml but he never measured it so just a rough guess.

    Premier Icon molgrips
    Subscriber

    Unfortunately, fuel additives will provide no benefits

    Not true in the case of diesel. Cetane improver improves the cetane number, which makes it burn more quickly and more completely. Only up to a point though – better quality fuel has a high cetane number already, so the additive won’t do as much. It has more of an effect the worse the fuel is. Essential if you are thinning veg oil with petrol. Also note that diesel is worse in winter – the anti-freeze additives in it lower the cetane number, so you will get better effect in winter.

    It may depend on the engine a bit too – the ECU may vary the injection timing with different fuel characteristics, but not too sure about that.

    coffeeking
    Member

    The vast majority of fuel additives are snake oil to the vast majority of users. Those who modify their engines may notice some improvement and additional ability from raised cetane/octane ratings but not many and will depend entirely on your car and it’s PCM. There’s no point in adding them and then using supermarket fuel, you might as well just buy the likes of vpower (d or p) as the additional cost per litre is about the same as a high quality fuel additive and contains chemicals with the same effects.

    What’s more there’s more than the odd anecdote about people adding D additives, especially cheaper ones, and commonrail diesel HP pumps failing.

    swampi
    Member

    I have been using millers diesel eco max additive for the last 3 years in my wifes work horse 118d, she does a 100 odd mile commute of ring road/motorway to work every day and millers gives 3-4 mpg better, def makes a difference, but i am using supermarket fuel, I bulk buy my millers and usually costs around £90-95 for 10 500ml bottles so it costs less than a quid per full fill up but saves us £4 ish

    Premier Icon molgrips
    Subscriber

    CK, any diesel engine benefits from higher cetane number – it’s not like octane rating with petrol. Also, most of those additives are 2-ehn, you can smell it. Very distinctive smell.

    you might as well just buy the likes of vpower (d or p) as the additional cost per litre is about the same as a high quality fuel additive

    You are right about the fancy fuel having the same additives in it, but it’s cheaper to buy it separately. In most cases, anyway. Costs about £5/tank to fill my car with nice diesel, and a £5 bottle of additive usually does several tanks. Of course a £5 bottle of neat 2-ehn from the bay lasts for ages.

    PeterPoddy
    Member

    Certainly seems to be the right approach if you have a Fiat. My dad’s Panda has been running quite rough recently. I’ve found that driving it like an Italian; bouncing off the rev limiter with every gear change and going everywhere flat out, has left it running much more smoothly and has improved the fuel efficiency

    Ahh, the Italian Tune Up!

    I Had a Ducati Monster that had a small issue from new with the fuelling. I took it back (6 miles on the clock) and they fixed it, but it still felt a bit rough so I took it back again, and was told that “You might have been too careful running it in. The mechanic has been out and ‘put the engine under load’ and it’s cleared up now”

    And that set the scene for the rest of my ownership, it ALWAYS felt smoother and perkier after a good ol’ thraipsing! 🙂

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