[Pikapolonica]

My father went to fill my car up on Saturday and accidentally put in 2-3lt of unleaded fuel before he realised and then continued to fill with diesel.

I only found out yesterday (Sunday).  Car sounds fine to me, didn't have any trouble starting it both Saturday evening or Sunday morning and to me sounded like a normal diesel starting up.

Would there be any issues with such a small amount?

[Dazzler]

Oh dear!  If it is still running OK I reckon I would top it up with more Diesel to further dilute the mix. But I'm no expert so don't sue me. 

Be interested to hear other's thoughts (particularly Tim) 

  Dad has dodged a bullet.

[Shambles]

There's an old but canny discussion here (worth a read)

http://www.pistonheads.com/Gassing/topic.asp?t=80442

[The Gonz]

It's uncanny how canny we can be with the intuitive response of brimming regularly for a while.
Not so sure the expression 'watering it down' wouldn't cause a stir.

[Pikapolonica]

So.................yes or no?  Something to be concerned about?

I'm just hovering under 1/4 tank, so will be filling up tonight.

[ibrokeit]

I personally wouldn't be too worried about it - if you were going to have problems you would probably already have them and/or any damage will have already been done.

Keeping the tank topped up for the next little while is probably not a bad idea.

Of course someone who is, or was, a mechanic might advise differently or better.

[Doggie 1]

With such a small amount I wouldn't be too worried about it.
As has been suggested, further dilute it by refuelling with diesel and I'd be surprised if there was a problem.

[Phil №❶]

As suggested, I would fill with Diesel so as to dilute the petrol / Diesel ratio. The petrol as it is encountered by the engine is going to detonate at the pressures created in the engine, so the lower the ratio the better. If the ratio is low enough, it should just aid the Diesel to ignite a fraction early which may affect your performance and economy for this tankful. I would then run this tank to as empty as possible, to eliminate any further fuel contamination.

[The Gonz]

The Diesel is denser and heavier than the petrol. If you can siphon the top layer until you can tell the difference between petrol and Diesel, go for it. However, you'll need to get the piece of hose only deep enough to collect the petrol, so not too deep.

Another approach is to force enough Diesel into the tank (after filling it at the servo) with a jerry can and let the petrol overflow out of the tank - but this is messy and wouldn't be very healthy environmentally or for your paintwork, perhaps.

On a warm day, if safe to do so, keep the cap off and let the petrol evaporate until there's only Diesel left, but it would be hard to tell when that is.

Given that the petrol will sit on top of the Diesel, I wouldn't be running it to empty at all - you're likely to get a high concentration of petrol at the worst possible time.

In all, every approach has its drawbacks. So if it were me, I'd assume I now own a car with a 25 litre tank and keep the tank above half full for a few weeks or months to come. You'll be fine.

[Phil №❶]

Given that Diesel is an oil and petrol is a solvent, wont they be homogenized in the tank, due to sloshing around.

[The Gonz]

Given that Diesel is an oil and petrol is a solvent, wont they be homogenized in the tank, due to sloshing around.

Yes, which is why eventually it won't be an issue, but the more Diesel in the tank, definitely the better.

[Phil №❶]

AFAIK, the tank is 25% full, so 75% more Diesel, then empty out should be ok. I like the evap idea, but how to stop dust entering while that occurs.

[jess]

small amount i would not bother about it put a tin of wynns  diesel injector cleaner in the tank as it will lube the pump as well fill tank  with diesel go for a good 25/ 30 mile run at different speeds and  then refill and forget about it

[sundiz]

Petrol mixes with the diesel.

Back in the old days you could add some pertrol to your diesel, so it would stay running in low temperatures (winter time). Petrol decreases the lubrification of the high pressure pump and therefore some added two stroke oil to lubricate the high pressure pump.

With modern diesels you are not allowed to do that. Fuel pumps need all the lubrication they can get. It would have been good if after adding the pertrol you would have filled it up with diesel and then added some diesel additive (as jess mentioned). That would have helped with the lubrication.

[cruiserfied]

Dont let it below 1/2 for next half dozen fills. Probably nothing to be concerned about.
There is the potential for damage like scoring the wall in the high pressure pump or damage in the injector, but only if it gets a big dose of petrol and it removes/washes the lubrication that the Diesel provides.
In saying that ive cleaned out vehicles that filled from empty and drove until it stopped, drained the tank, flushed the lines and a new filter. Still going fine as far as im aware.

[Phil №❶]

I stand corrected, thanks cruiserfied 

[cruiserfied]

I stand corrected, thanks cruiserfied 

About what?

[Phil №❶]

I said, run the tank dry after a refill. 

As a tech, your advice takes priority IMO. 

[cruiserfied]

I recon Jamie is probably best qualified to advise on fuel concerns

[Phil №❶]

What, EAT BACON

[cruiserfied]

That does solve 99% of all issues.

Maybe some bacon in the tank will dissolve the petrol.

[Phil №❶]

It should lubricate, at least.

Note, this is a joke, do not put bacon in your tank!

[CraigB]

Maybe some bacon in the tank will dissolve the petrol.

It'll add oils/fats to lube that fuel pump

[cruiserfied]

Sure would be the best smelling exhaust gasses ever.

[cruiserfied]

Note, this is a joke, do not put bacon in your tank!

Yes that was definately not Technical advise.

[Wingerdave]

Easy answer...... 3-4 ltr in a full tank is not a problem. Before we started getting "winter diesel" here i always put 10% unleaded fuel in the old Opel 1.6D. Never had a problem of any kind.

Plus, your fathers faux pas was a one off thing (hopefully), so no worries.