Well… 

 

I got a phone call from the misses last night, she went to top up the tank with diesel but mistakenly put in 7L of unleaded. 
 

I told her to brim it with diesel and bring the car home approx 4 miles. 
 

should I drain the tank? She said it ran fine on the way home but I’m a bit nervous. 
 

what the best way to drain these tanks? 
 

🍻 

Hi, are you able to estimate probable proportion of petrol to diesel? If reasonably low, I'm sure that there will be no issues.

1 minute ago, Warrior193 said:

Hi, are you able to estimate probable proportion of petrol to diesel? If reasonably low, I'm sure that there will be no issues.

Thank for the reply! 
 

it’s a 45L tank and she filled it right up after realising the mistake. So there’s 38L diesel and 7L petrol in there

Checking a little on Google, there seems to be a few saying 5% or 7.5% is max safe amount.

 

You have roughly 15% mix, it will likely shorten the fuel pump life, but you need to decide whether to roll the dice, you could run the car around as normal, and keep topping up often with diesel, so the percentage drops quickly.

The lack of lubricity introduced by the petrol is the problem here. The entire fuel system depends on the fuel for lubrication.

 

Ideally you should drain the tank and refill with diesel but it's a bit of a pain since the filler neck has an anti siphon device. One option is to disconnect the fuel supply line from the tank at the fuel filter and route it into a container then manually supply 12 V to the lift pump in the tank to run the fuel out of it.

 

If you don't want to go to that effort, you could get a bottle of Millers Diesel Power Ecomax and add several shots of it to the tank - leave it a few hours to mix through the fuel in the tank. It includes lubricity enhancers and would probably counteract the effect of the petrol, but I don't really know how much would be needed.

47 minutes ago, INV3RSE said:

went to top up the tank with diesel but mistakenly put in 7L of unleaded. 
 

 

Most breakdown companies will cover this if you have cover. Give them a call and ask.

Please note - I am not a mechanic or expert in anything.

 

If you're taking the risk as chimaera has put above also keep topping up the tank with fresh diesel as you use the vehicle to dilute the petrol as much as possible, even 2 or 3 litres at a time (the pumps will supply this small amount but IIRC need about 5 litres for pump delivery to meet accuracy requirements).  Petrol is a powerful cleaner so will wash away too much.

 

Better still as Phil886 has put if you have breakdown cover contact them, AA specialise in this DAHIK.

 

Edited 5 November, 20223 yr by nta16
ETA: Please note - I am not a mechanic or expert in anything.

The easiest way to drain them is to take the hose off the fuel filter and pump the fuel out from there with a separate transfer pump. Run it until it's dry, then put a bit of diesel in the tank, and make sure the pump's  pulling clean diesel. The bodge is to do the same, but run the lift pump in the tank either by flicking the key, bridging the relay or using a diagnostic tool to run the pump. 

 

As above, the big risk is that the high pressure pump, and to a lesser extent, the injectors, won't be getting lubricated properly, so might fail sooner than expected. There's no real way to say if that's in 10 minutes, 10 days or 10 years. 

I’m debating the dice roll.. 

 

The car had half a tank of diesel in it before the 7L of petrol was added then filled it right up with diesel, would this make a difference? 
 

Unfortunately we don’t have AA cover or any cover that would come and sort it out 😔 

The ratio will still be the same, 7lt. on a 45lt. tank.

 

Might be a good idea to drain that off if you cannot afford the repair bill, it's truly luck of the draw if it gives way sooner rather than later.

I'd roll the dice at that ratio I think. Fill it up every time you can squeeze another 5 litres in.

What capacity of jerrycans do you have?

 

Ideally you want at least 20 litres, if you have 2 making 40 litres then you are laughing.

 

This is the procedure I would use whatever capacity of storage you have, use the preceeding advice as to how to pump the fuel out.

 

Pump out the 20 litres (for this example), drive to closest garage and fill tank with diesel.

 

When tank drains down to 1/2 or 3/4 (your choice) refill it from the contaminated fuel jerrycan.

 

Continue dosing like this until you have used all the contaminated fuel.

 

I helped a friend who had filled petrol on top of a nearly empty diesel tank, I siphoned off 2 jerrycans of mostly petrol and he refilled with diesel, I tried the mix in a lawn mower but it smoked and misfired so I was adding it gradually to every tank of diesel on my MK1 Octavia which had an old school mechanical pump, I went up to 10% petrol without any problems, in fact it ran sweeter.

 

Yours if it is a common rail diesel I would not exceed 5% so would drain out 20 litres minimum, if its an old school mechanical injection pump then like Pete I would go for it at the current ratio unless it is running or starting badly.

Edited 5 November, 20223 yr by J.R.

Thanks everyone I appreciate all the comments, I’m going to have a think about what to do. 
 

Im edging on the side of see what happens and top up frequently but obviously do understand it is a risk. 
 

iv just spent £400ish on tyres few bits for the mot so cash it tight right now
 

What a bummer eh? 😆 

Given your username I'm wondering if the guilty party really was your wife 😆

With my suggestion it wont actually cost you any money (long term) if you have a jerrycan, it will give you piece of mind and might actually save you money if fuel prices keep increasing!

At that ratio I too would roll the dice, the petrol will act like a cleaning agent.

1 minute ago, J.R. said:

Given your username I'm wondering if the guilty party really was your wife 😆

😂 This made me laugh

Looks like you have plenty of excellent solutions to the problem, just need to put it into action.

 

Best of luck with it all.

6 minutes ago, varooom said:

Looks like you have plenty of excellent solutions to the problem, just need to put it into action.

 

Best of luck with it all.

Thankyou 

My wife did the same thing years ago, topped up the tank with diesel and also added cooking oil, the cheapest available, put in about 2.5 litres, it worked, didn't experience any probs, had the car for 3 more years after the event

As a comparison for making a decision - I once had a misfuelling with a Volvo D40 engine, the pump operator had changed shift between me requesting fuel and my arrival at the fuel pontoon - resulting in me being handed what I believed was a diesel hose (out of sight of the actual pump) and putting approx. 120 litres of petrol into a 200 litre tank. Refuelled at Isle of Wight after discovering mistake. Saving grace may have been approx. 50 litres of pretty old diesel that had probably been in the tank for a year.

Engine ran fine from Poole, and fuel pump suffered no apparent damage - was still running fine three years later when I lost her.    

Please note - I am not a mechanic or expert in anything.

 

Bear in mind the pumps may say something like 5 litres minimum but I can assure you you can use less so you don't even need to wait for 5 litres use, every time you add more diesel you are increasing its ratio and decreasing the ratio of petrol.

 

If you're worried about this use a pay at pump then there's no cashier to debate with if you're worried about that.  A couple of months ago I bought 2 or 3 litres (or even perhaps less I forget) of Esso Synergy Supreme+ as it's ethanol free to put in my neighbour's lawn mower to save me having to clean out the water and rust again, paid at the pump, no minimum charge, no additional charge on the card either.

 

An alternative is to prefill a 5 litre can and top up your tank with that and keep refilling it and the car when the can is empty that way you will always draw at least 5 litres from the pump.

 

Edited 5 November, 20223 yr by nta16

Are you seriously suggesting that the OP tops up his tank every time it drops by 2 litres?

 

What possible benefit would that bring aside from perhaps amusing you?

 

He has a maximum of 15.5% petrol content and the car is running fine, it will be half that or less if he drains some to re-use later, if he chooses not to then topping up after using 2 litres will reduce the percentage of petrol by 1.32%.

 

Following your advice would have the OP stopping to refuel every 20 odd miles to reduce the concentration by 1%, it will never get to zero so when would you have him stop playing your game?

 

You must be having a laugh?

Edited 5 November, 20223 yr by J.R.

Do yourself a favour @J.R. and add him to your ignore list. 🙂

So now we know where Liz Trust and Kwasi Kwarteng got there calculations from.

 

Hopefully INV3RSE can see my point, and for some 20 miles can be a day or two of driving or even more, if a single journey was 30, 40, 50 miles or 3, 4 or 5 litres use of fuel that would be a convenient top up point.

 

Despite what my troll has put I didn't put every top up has to be at 2 to 3 litres of use, my point was that 5 litres need not be a minimum.

 

I would have a 5 litre can and fill that and also top up the tank of the car, even if the car only needed 2 or 3 litres.  Any stops I would top up the tank from the can as much as possible, rough mpg would be known, even if only a litre or two or three, I'd not want to overfill.  When stopping at a fuel station I would top up the car and the can again even if the can or car or both only needed a few litres between them.  The quicker the ratio in the tank is brought to safe level or better still 100% diesel the more content I'd be.

 

To me it'd only be like topping up a leaking radiator, I'd do it as frequently as convenient and safe to me, I'd not expect my wife to do the same, but then my wife has never misfuelled whereas I have.

 

If that's extreme I'm sure INV3RSE can decide how far or close he (assumption) wants to be to my extreme.