OT Another reason the get rid of fossil fuels.

What makes you think cleaning the particulate filter causes a problem?

They need to burn out the 'ash' somewhere, typically on long higher-revving journeys, given the 50mph stretches of the M4 are where it passes through urban areas, I suppose it might help to not inject the extra diesel to superheat the DPF in those areas, but it's not as though it happens all the time the car is at motorway speeds.

I'm just quoting this year's Reith Lecturer, one or more of whose lectures I heard on the Beeb a few weeks ago. I'll have to re-listen 'cos I can't remember the specifics. Or you could.

Thanks for that. Downloaded and I'll have a read later.

Erm yes, I agree. I also downloaded the following two lectures. Altogether an interesting read, so again, thanks for that link.

Not all of them. Some have to have an additive put in the fuel now and then to clear the filter.

The urea solution is to reduce the NOx not clean the filter.

there are companies (redex, stp, wynn's etc) selling DPF fuel additives, I've never heard of any diesel car requiring them, presumably they're for the gullible?

Not requiring them, but they do reduce the fuel used to regenerate the filter.

No.

A bit of extra diesel at £1.20 odd a litre, or a special additive for £10+ a bottle?

I was just about to make that very point. Unless the additive means that the DPF will require less regeneration from now on for some time in the future, you'd be better off burning extra fuel than buying the more expensive additive.

How frequently (eg mileage or amount of fuel used) does a typical DPF need regenerating? I ask because I've never been aware of it happening when I've been driving - there's no temporary change in performance or warning light on the dashboard.

Do the RedEx etc additives have any other effect than regenerating the DPF? I think I once bought one that claimed to clean the fuel injectors of any buildup of crud - that was for my first Pug 306 (1.9 turbo diesel as opposed to 2.0 HDi) which started hiccupping on gentle acceleration, and the garage recommended a bottle of it. They were about to put in some of their own stock - and charge me more than the Halfords price, so I said I'd get it myself ;-) That was long before diesel cars had DPFs and pouches of urea - probably mid 90s.

Its only used very service, not every fill. And doesn?t cost that either.

Only if the computer is reprogrammed so it knows they are there. Otherwise it will just do its normal cycle.

Probably.

Apparently some Pugs do have an onboard DPF fluid reservoir

There are some cars witha second small tank of "Blue" - what ever that is.

Just one of those additives and they claim it reduces fuel consumption and it likely does with the engines which measure the pressure across the filter and burns fuel to burn off the soot in the filter if it actually burns off the soot itself instead so that isnt triggered.

That is to do with reducing NOx, not particulates