To Add or not to Additive

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GiveMeABreak
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To Add or not to Additive

Post by GiveMeABreak »

I'd like to know what the consensus of opinion is from HDi vehicle owners concerning the use of Diesel fuel additives (for clarification - not particulate filter additives).

The likes of Wynns Injector Cleaner, Redex Diesel Treatment Cleaner and other similar products etc., all profess to clean the fuel system and say they are safe for all Diesel cars - however, PSA say in their HDi general recommendations:

"CAUTION: The addition of additives, such as fuel circuit cleaners / remetallisers, is forbidden"

I know this is the same for other manufacturers including Volvo. I tend to use a premium Diesel like Gulf Super Diesel every 3-4 tankfulls which has a higher cetane level, but is supposed to contain other additives to clean the fuel system. On my preoviuosu HDi, I do recall buying some Diesel fuel treatment at the station. After filling up with some premium diesel, the manager mentioned to me that it was pretty pointless putting that in as the super diesel did the same thing - so I didn't bother with it. Since then, and with the C5 X7, I've never used any additives.

So does anyone know why PSA tell you not to use them?

dnsey
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Re: To Add or not to Additive

Post by dnsey »

I suspect that it's mainly because of the risk of contaminating the DPF.
Most additives probably do no harm, but they have to cover themselves!

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Stickyfinger
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Re: To Add or not to Additive

Post by Stickyfinger »

I have used an injector cleaner once, it worked. Cured a slight hesitation I noticed when I first got the car, not used any since.

I have also used a "tappet lube" when I first got the Activa, only good oil since, it too cured the problem (slight tap tap when cold).

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white exec
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Re: To Add or not to Additive

Post by white exec »

Maybe no more than a general warning about additives in general - eg for engine and transmission oil.
Cetane improvers are what differentiate cheap diesel from the good stuff, but as there are so many substances that can be used to achieve this, maybe, as you say, they are just covering themselves. After all, if there's a claim, and they can point to the presence of ABc, it's one less claim to have to fork out on.

I regularly use either Wynn's Diesel Fuel Treatment, or Millers Diesel Power Plus (both similar products), and they both work well - as system/injector cleaners, and as cetane improver. More low-end torque, less down-shifting, and a quieter engine. I run both our diesels on Repsol standard (e+) diesel, which behaves very much like the excellent Esso 2000 (and subsequent fuel) available in the UK. Fill up with supermarket diesel, and it's generally a miserable experience, with loss of low-end torque the most obvious failing. Not everyone will agree on this.

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Stickyfinger
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Re: To Add or not to Additive

Post by Stickyfinger »

I must say I have never noticed a difference in fuel choice with my C5 power wise, I use good every 4-5 tanks (ish) just for cleaning really.
I DO notice a bit of a difference in the ACTIVA with higher octane fuels however, but being petrol they are more effected by it.

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Re: To Add or not to Additive

Post by GiveMeABreak »

It's just that the wording "forbidden" is slightly dramatic - so I was curious as to whether there was something in these cleaners that could adversely affect any part of the HDi system in particular - as not all HDi engines are fitted with DPFs - and the warning was under the HDi info specifically...

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white exec
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Re: To Add or not to Additive

Post by white exec »

Yes it would be useful to know the basis for the prohibition.

It is possible to use substances such as acetone as a cetane improver, and I can see every reason for the vehicle manufacturer to prohibit that. What it could do to seals and hoses doesn't need spelling out.

Don't know of any mainstream diesel fuel treatment that uses acetone, though. Several of the good ones use a compound of naphthalene, known to be an effective cetane improver. (If you wikipedia 'cetane improver' you will find there is a bit of history of using dissolved mothballs to improve the performance of diesel fuel.)

The MSDS sheets for the Wynn's and Miller's products make interesting reading. Some other vendors of similar products have been reluctant to make this information avaialble, and some of the treatment products on the market have been revealed to contain little more than diesel! The two above have a proven pedigree, though.

Peter.N.
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Re: To Add or not to Additive

Post by Peter.N. »

In view of the fact that these engines can be good for 300-400k miles with regular oil changes I wouldn't think additives would be necessary.

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Re: To Add or not to Additive

Post by KP »

The other additive not mentioned for diesels is 2SO. There are long threads kicking about the net regarding it and I for one notice a quieter engine with it and not much if any mpg improvement but reduced engine noise does it for me :)

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Re: To Add or not to Additive

Post by JohnD »

Stickyfinger wrote:I must say I have never noticed a difference in fuel choice with my C5 power wise,.
.
On another forum one of our members was a chemist in the petro-chemical industry and prior to his untimely death, he was the UK representative on the European Standards Committee for Motor Vehicle Fuels. In answer to many questions and statements regarding different diesels, he wrote a long essay which I copied and filed. This is extracted from it:-

After market products like Millers improve the cetane rating of standard diesel, but only when the engine is cold - interestingly it doesn't help a hot engine - so cold starting is usually quieter but no difference to a hot engine - and Millers does provide good, additional pump lubricity.
If you add Redex or Millers or switch to a branded fuel, then any change to the cleanliness of the injectors won't show itself for quite a few hundred miles, but pump lubrication and maybe a higher cetane rating will show an effect much sooner - depends how much old fuel was in the tank and fuel lines - and how much the old fuel dilutes the action of the new fuel.

And don't be dismissive of supermarket fuels. Is there a difference between supermarket and branded fuel ? - there can be - but often there isn't.

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GiveMeABreak
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Re: To Add or not to Additive

Post by GiveMeABreak »

Quite interesting John - especially regarding the supermarket fuels v branded fuels debate. I stopped using supermarket fuels quite some years ago after the mix up with the fuelling pump colours at a Tesco which resulted in my Xantia HDi getting a tank full of Petrol! My mechanic wondered how the hell I actually drove to the garage for a clean up, as opposed to 'rocketing' it there!

I now used Shell or Gulf - wherever possible and either the V-Power Diesel or the Super Diesel - it costs a bit more - but I no longer use additional fuel additives in addition. I think it's a matter of maintaining the system over time like anything. My cars always seemed to stutter occasionally - or feel a bit'rough' idling / accelerating on the old supermarket fuels - something I no longer have since switching for the last 5-6 years to not just the branded fules, but the premium branded fuels - so I think you have to go with what works for you. :)

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Re: To Add or not to Additive

Post by darbuck »

Ive used a few over the years when i was taxiing some work some don,t never noticed any signifigant increase in mpg but did help with emmision tests but i f have found throwing a fiver of kerosene in every couple of tanks helps just as much thats with putting up spaceship miles on cars as in 3 and 400,000 miles on them all diesel of course everything else failed on my cars but never the engines using this method so if it ain't broke.