Low sulphur fuels

It was the latter. It only became a real issue with the advent of catalytic converters on cars which caused 'storage' of sulphur which was then released under certain conditions to give the characteristic hydrogen sulphide 'rotten eggs' smell which was common in the 1990s but less so now.

More info on my (out of date) page at

Cheers

Chris D

Absolutely correct for petrol engines....but not quite so for high speed diesels. Sulphur in diesel fuel increases its lubricity, but does cause pollution and smoke. When low sulpur fuels first came in, there were issues with premature injection pump wear, and seal failure, but these seem to have been overcome now. Also, its possible to buy over the counter additives, such as 'Diesel Plus' which are meant to improve the quality of low sulphur fuel.

OTOH, as far as our old engines are concerened, I don't think it makes a blind bit of difference, and they'll be perfectly happy on low sulphur fuel,indeed, I've run a CS on a mixture of paraffin and 10% lubricating oil with no ill effects.....so they're not *that* fussy.

Regards

Philip T-E

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember Joules saying something like:

As for diesels...

There was a tremendous kerfuffle some years ago when the introduction of low-sulphur diesel fuel led to the unexpectedly early demise of fuel injection pumps on trucks and vans. It turned out the sulphur content was providing a previously unrealised but vital lubrication component and the lack of it became obvious when trucks ground to a halt with expensive pump failures.

Oops.

The situation was rectified by adding lubricants to the fuel, among which is biodiesel. It turns out that 1% - 2% biodiesel restores the lubricity back to the previous standard.

LOL it wouldn't be anything to do with the sulphur in organic compounds, typical political intervention... What can we rename Sulphur as ??? do you think the environment will be fooled too.

Thanks guys, you have all been a good source of information. Reading between the lines, old engines are a much better bet than the modern varieties, as they are far more tolerant of varied fuel sources... Maybe the modern engines have something to learn from the past afterall.

Joules

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember Joules saying something like:

If you do a google for the sulphur content of biodiesel, you'll find it's minimal; something like 15ppm. Old petro diesel had 500ppm and Ultra Low Sulphur Diesel (which caused the problems) had 30ppm.

You can see that the lubricity properties of biodiesel come not from the sulphur content, since 1% of that will contribute an utterly minuscule amount of sulphur to the ULSD.

I recall reading a couple of years ago that the platinum compounds from catalytic converters lay in such quantities by urban roundabouts that it was almost worth processing for the precious metal content!

Further, my MOT man tells me that cats don't work at all when cold and only poorly until they warm through. Then they have to burn off the cold start residues and it might be as much as twenty miles before they are working as the maker intended. To be fair, this was a little while ago & things might have improved since then.

regards,

Kim Siddorn.

But you have a Volvo, and despite their many good points, cat design was never Volvo's strongpoint. Time was when you could smell out a cat-fitted Volvo that had been filled at a Jet station, just by the smell of rotten eggs. (I lived in Newcastle at the time, where Jet was more common, being local and cheap)

Modern cats are smaller and lighter, so they heat up more quickly. The substrates are now ceramic with a thin active film on them, rather than the old metal foils. This gives more area / $ and also less thermal mass to heat up first. Modern EMS can also monitor cat temperature and use a "rapid heating" cycle on startup to get them warmer, faster. Cats also have better airflow than previously, so they no longer have the "blocked exhaust" effect to throttle an engine.

There's still a problem with cats being better on long runs than short, but it's nothing like so serious as it was.