Paulo P

iTrader: (42)

Hi All

My sister has a 306 diesel and her boyfriend put petrol in it the other week It was only a tenner so I got her to fill it to the brim with diesel and it started an ran fine. She is now down to a quarter of a tank and wondering what to do.

Do Petrol & Diesel mix?

How low should she let it get before filling it with Diesel?

Thanks in advance

kend

Depends on how old the car is.
New/current diesels have very low tolerances, and if you put petrol in and run engine it will cause fairly major damage. Usually the suggestion in new diesels if you do this is to have the tank drained down, and refill before starting up.

Older diesels usually ok. It used to be (>10 yrs ago) fairly standard practice in cold countries to put 10% petrol into every tankful to stop the diesel freezing.
The 306 likely to be ok as the engine design is fairly old, I would have thought topping it up with diesel frequently ( not letting the tank get too empty for a few weeks) would be sensible, so as to keep diluting the petrol down further.

Paulo P

iTrader: (42)

Thanks for the reply. The 306 is a 94 L reg. The car runs like nothing had happened apart from when it's cold when it doesn't like idling but I guess that's understandable.

Do petrol and diesel mix though or does the petrol float on top of the diesel?

Thanks

kend

I believe it mixes, otherwise adding petrol wouldn't have stopped diesel freezing

Paulo P

iTrader: (42)

That's what I thought but my sister being a dopey girl thought it floated. I just wanted it confirmed.

Thanks

ajm

LOL!

I can confirm that diesel and petrol are completely miscible (they mix! )

Paulo P

iTrader: (42)

ta

brickboy

I'd get her to fill it up again now with diesel, and it should be fine.

If it's already gone through 3/4 of a tank without the injection pump destroying itself then it should be OK -- the pump relies on the diesel fuel's lubricity to keep working, and petrol isn't such a good lubricant

The pump is the weak spot, if that's OK then the rest of the fuel system will be too. As said above, modern common-rail and VAG PD diesels have pumps operating at very high pressures -- 20,000+ psi is normal, and the PD motors run at 30,000psi at the injectors -- so tolerances are very fine and they need the lubrication of the diesel fuel. Older diesels with mechanical fuel pumps -- like the older PSA units -- aren't as fussy

Might be worth getting her a bottle of Miller's Diesel Plus (about £6 from motor factors) which adds lubricity, and dropping some in the tank for the next couple of fills.

Get her to use the new Shell Extra diesel if possible, it's good gear

Paulo P

iTrader: (42)

I'm getting her to fill up with diesel tomorrow and I'm going to replace the fuel filter tomorrow night because it must be due anyway and can't harm.

I didn't know that about the fuel pump though I guess if it was going to go due to this then it would have gone by now

What does diesel plus do? Is it there purely for lubrication?

Thanks

Mice_Elf

...and never let her boyfriend fill up her car again unless he has DIESEL tattoo'd onto the back of his hands.

brickboy

Paul, by the sounds of it, it's done no harm. If it's already gone through 3/4 tank of the petrol / diesel mix without misbehaving or expensive noises the car should be fine.

If the pump had been damaged it would have grenaded within no more than 100 miles, I would think.

Good idea to replace the fuel filter, they get gunged up easily anyway.

The Millers stuff is a lubricity, anti-soot and cetane boosting additive, some people swear by it and others don't think it makes any difference. But it will add lubricity while the petrol is being eliminated.

If you can't find it, Redex diesel additive does much the same thing.

Paulo P

iTrader: (42)

He's not allowed near her cars now he slips the clutch on her scoob and puts petrol in her diesel She made him go and buy another car while his is off the road and he bought a 1.2 nova that'll teach him

Paulo P

iTrader: (42)

brickboy

it must have done 300 miles + I would have thought to have used 3/4 of a tank of fuel. She has to go to halfords or somewhere to get a fuel filter so I'll get her to look out for some of that stuff and chuck it in, better safe than sorry

J4CKO

iTrader: (1)

Funnily enough the lad I share a lift to work with was talking about this today, he has a K reg 405 TD, he said he did it and it didnt cause any problems, he is on 155,000 miles and it still runs sweet enough.

Paulo P

iTrader: (42)

MattOz

Paul, YHM

Paulo P

iTrader: (42)

Thanks Matt. YHM back