Thoughts on diesel/petrol mix

While filing my ten year old ford escort van with diesel this morning I was looking at the price of petrol.

I got thinking about a 90% diesel 10% petrol mix similar to what is suggested in the handbook for winter use.

Taking in mind that this would increase the calorific content of the fuel, what would you opinion on using a mix of this for a prolonged length of time.

I was thinking of a slight increase in engine wear (not a great concern with a ten year old rusty vehicle) against a small increase in power and fuel saving being able to go up the gears more quickly.

Reply to
Andrew Carr
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As it'll drop the viscosity of the mixture you'll get less fuel injected , which'll more than overcompensate for the negligible change in calorific content.

Reply to
Duncan Wood

Diesel has the higher calorifc value, so mixing petrol in will reduce it. As for using it over a longer period of time, it'll increase wear on the fuel injection components, and also on the upper cylinder components.

If anything, it'll reduce performance, and besides it's an escort van. It takes a lot more than a change off fuel to get them to move any quicker.

Reply to
Moray Cuthill

No. It's injected by volume. The same volume will be injected whether it's diesel or a mixture of fuels and the petrol will be ignited along with the diesel, so nop problem.

But as to the OP's question, I say go for it if you have it, especially for an old banger. Whenever I have been called out to people who have filled at the wrong pump, I have always put the mixed fuel in my old banger of a truck if it's mostly diesel, or in my daughters old banger cars if it's mostly petrol. Although if I'm at all iffy about it I don't put it all in in one go.

It's yet another good reason for driving old bangers, you can get away with far more than newer vehicles.

Steve

Reply to
shazzbat

concern with

Is it worth bothering for the price difference? It's only going to be a real benefit if you do really high mileage. Correct me if I'm wrong, but IIRC there is only around 10p/litre difference, so you'd be looking at about 50p saving per 50l, and that's probably more than a tank full. So what's that gonna be? Around 1p saving for every 10 miles (very approx guessing mpg etc)?

Reply to
petermcmillan_uk

The message from "Duncan Wood" contains these words:

Really? I'd have thought the runnier the fuel the more easily it'd get through the holes. But even then only to the extent that the injector pipes are springy 'cos it's forced in by the pistons in the injector pump. It's not like petrol injection where the amount is controlled by time from the high pressure rail.

Reply to
Guy King

I have a friend who has been running his 2.0 diesel vectra on vegetable oil for some time, costs him about 25p a litre only problem being it smells like he's pulling a chip shop behind him.

Even though it's illegal he knows of quite a few other people who are doing it including one particular 4x4 owner who took his for it's MOT with half a tank of veg oil in it, and it passed :)

May be worth considering if the fuel prices keep going up the way they have been, just don't let Mr customs and excise catch you.

Reply to
tollermccallum

What stuffs you is the transfer pressure in the pump (which determines how much fuel can get in between the pistons before they're pushed together) drops & the leakage past said pistons increases, it can be significant with temperature so some commercial plant pumps with hitorque rise characteristics have secondary viscosity compensation systems.

Reply to
Duncan Wood

I thought it was perfectly legal so long as you declare it and pay the relevent duty.

Of course, you might be slightly absent minded when topping up once in a while though...

Reply to
Stuffed

problem

Yeah, the problem is that the tax costs a LOT more than the veg oil. To be honest, I don't think it's really worth using new vegy oil, and paying tax because you'll probably only save a few pence if you're lucky. Of course, if you can get used vegy oil really cheaply then you could make a nice saving.

Reply to
petermcmillan_uk

veggie oil is out, a neighbour works for customs and excise and take great pleasure in dropping people in it.

Reply to
Andrew Carr

You cannot use just vegetable oil - there are a lot of things in there that do a good job of gumming up the works. You can process it with sodium methoxide and then use the result after it's separated to good effect though - sadly the production cost and the tax - even the reduced rate for biodiesel push the cost up to damn near the same as DERV

I've made fuel oil i this fashion which works fine in a kerosene heating boiler and also in a diesel engined boat but there's no cost saving for (legal) road use.

Reply to
Chris Street

It was somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember snipped-for-privacy@virgin.net (tollermccallum) saying something like:

It's not illegal if you tell C&E and pay the 20p or so duty on it. Just tell your friend to make sure he has a receipt for it in the car.

Reply to
Grimly Curmudgeon

It was somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember "Andrew Carr" saying something like:

He must be a real shit. Only way to play that kind of wanker is to beat him by knowledge of the rules.

Reply to
Grimly Curmudgeon

It was somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember Chris Street saying something like:

In a properly designed heated system it works fine and problems are avoided. The trick is to start and stop on fuel oil, thereby flushing the pump and injectors with diesel before shutdown.

Reply to
Grimly Curmudgeon

Well yes but like I said - not just vegetable oil.

Reply to
Chris Street

I ran a Rover 620 on just Vegtable oil for probably more than 2000 miles. Initally I used to mix it with white spirt (as a lot of sources had recomended) in a 10 to 1 blend, but then I just didn't bother with that in the end.

Only problems I had were in cold weather. It became slightly harder to start (even then I still rarly needed the glow plugs) and it would sometimes stall easily for the first couple of minutes until it warmed up. The L-series was always a good starter I'll conceed though.

As far as I can tell it caused no damage and ran just as it had when I stuck derv back in it. I'll agree that it's probably not the most conclusive test for running a car on veg oil long term.

Reply to
Delgardo

Wasn't that a Peugeot XU series engine??

Andy

Reply to
Nik&Andy

Nope, that was the 1.8 lump Rover used in the 200/400 series. The 2.0 as used in the 600, "bubble shaped" 200 and early 75s was their own.

Reply to
Delgardo

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