Now then young Sir, I’ve just been reading in my new copy of the magazine, which arrived this morning, about Mike Davis’s thoughts on using biodiesel in his car. I hope that you referred him to our previous dialogue on the subject. 

I started making biodiesel in 2008 and have run four Skodas on it since, all either PD injection, or the even older distributor pump, with no problems, even though I have used 100 per cent biodiesel in the cars. Waxing in winter might possibly have taken place, I realised, but I have been adding Coldflow additive to winter grade fuel to prevent that. The fuel filter had to be changed shortly after starting with bio-diesel, because its cleaning effect shifts a lot of old deposited matter, but there has never been any problem with seals and pipes. I made a point of taking the bung out of the top of the fuel tank on a few occasions, for a sneaky look, but never saw anything other than pure fuel in there. I also always put my homemade fuel through a one micron filter on its way into the tank.

However, I am now going to have to stop making my own diesel by trans-esterification, as I am changing my 2010 Octavia Scout for a 2015 Octavia Scout (we wanted DSG), and I have been well warned that common rail systems do not like bio diesel, even though pump diesel is about seven per cent biodiesel content. 

So I am going to feed the rest of my biodiesel stock in bit by bit ñ probably two to three litres to a full tank, to dispose of it, and try to find a buyer for my old production plant. Failing that, I will have to take it down to the tip, as it owes me nothing. If your correspondent Mike Davis wants to contact me, he is very welcome to have a chat, I think his wife’s car should be fine on biodiesel, but if he wants to start making it then he will have to source some clean, used, liquid chip oil before all else.

Keep up the good work, 

Richard Hogarth

Very good of you to update me Richard. “Young Sir” ñ I do like that. Are/were you in sales?

Since Mr Davis did not make any suggestions about manufacturing biodiesel, it would have been a distraction to have mentioned that possibility. But now that you’ve gone common rail with the Octavia, along with the rest of the world, it seems that DIY manufacture is really no longer viable, and the only way we’re going to see biodiesel now is as a minor component of our pump fuel. I discovered recently that the percentage of biodiesel in pump diesel is dropping slowly every year, as the oil companies find it easier to source bio-ethanol to put in petrol than to source biodiesel to put in diesel, and meet their “Renewable Fuel Obligations” that way ñ the bioethanol coming from the sugar from sugar beet, apparently. But I am at a bit of a loss though as to why the renewable content has now seemingly been allowed to slip below three per cent (2.85 per cent UK 2016) as I thought that oil companies were obliged to add more than that. I know that at one time it was on a climbing scale, rising to a maximum of seven per cent, although later cut back to five per cent. I’m not sure if that was because of engine/fuel system problems at seven per cent, or whether there was a supply problem. I will try and find out what’s happening.

A great pity, in many ways, because there was something of a thrill in using pure biodiesel, as I did for a while in an XUD-engined Peugeot 405 back in the ’80s. It does make you wonder how dirty in today’s emissions terms our cars were back in those days. Quite filthy, I suspect!

I will forward Mr Davis your contact e-mail, and you may well hear from him, or you may not!

P.S. It seems that all the incentives for such raw vegetable oil derived biodiesel, as opposed to recovered vegetable oils, will be phased out by 2020! That’s why the content of biodiesel in DERV has been falling, and will, evidently, continue to fall, as supplies of recovered oils are limited. It’s all to do with the fact that vegetable oils are, it is claimed, displacing vital food crops in developing countries, which is a bad thing. There is still scope for other sources of vegetable and lichen and seaweed-derived biodiesel, but I have a feeling that the romantic days of biodiesel that were once so exciting are now all gone ñ in the cause of political correctness. Do they stop people in poor countries with starving populations from mining gold, or diamonds ñ and put them into the fields to grow crops? No I think not! What a silly world!

Doc