What effect would 1.2 litres of petrol have on a diesel engine?

adamrawling · Nov 28, 2005

Right then gents,

Today, as I was filling my 2.0fsi up with petrol (don't worry about me!), some bloke enquired about what effect 1.2 litres of petrol would have on a diesel. He said he was filling his motor (a Vectra) up with juice but by the time he'd realised he'd got the wrong nozzle, he'd put 1.2 litres of petrol in it. He said the tank was pretty much empty and was contemplating just filling the rest of the tank up with diesel and carrying on regardless.

Would the petrol (approx 2% of the tank capacity) be so diluted by the diesel that it wouldn't matter, or would it wreck the engine?

I suggested that he phone the RAC or someone and ask. By the time I'd finished filling up and paid, he was sitting in his car with his phone to his ear.

So I'm just curious, would he have got away with it if he had just driven the car off?

Dandle · Nov 28, 2005

Thats such a small amount he should be fine if he filled the rest of the tank with deisel. I would just take it a little easier for the next tank of fuel.

h5djr · Nov 28, 2005

Probably. My brother drives a diesel VW Polo and a few months ago had a mental block and filled his tank with unleaded petrol by mistake.

He phoned the AA and they said that, providing he had some diesel left in the tank when he filled up the petrol would sit on top of the diesel as it's much lighter. They suggested he drive home gently ( it was a Sunday) and in the morning get a garage to drain the tank and flush it out and refil it with the correct diesel and everything should be OK. It was and he had no further problems.

Putting diesel into a petrol car is more of a problem as it sinks to the bottom of the tank straight away.

As he had only put a small amont of petrol in he would not had to much of a problem, but it would have been a good idea to try and syphon the petrol off the top of the diesel at some stage.

adamrawling · Nov 28, 2005

[ QUOTE ]
Putting diesel into a petrol car is more of a problem as it sinks to the bottom of the tank straight away.

[/ QUOTE ]

Top knowledge - I didn't know that!

Thanks.

(I could make a joke about diesel being heavier than petrol .... but I won't!)

/ubbthreads/images/graemlins/beerchug.gif

cdb2 · Nov 28, 2005

LOL

"I could make a joke about diesel being heavier than petrol .... but I won't!" - that's Yak's job!

bunny · Nov 28, 2005

Wouldn't worry mate - in Germany we used to put some petrol in diesel cars to stop the tanks freezing in winter.

marriedblonde · Nov 28, 2005

Yer mercedes used to recommend putting petrol in with the diesel in cold weather years ago.

J.

h5djr · Nov 28, 2005

Who said Diesel was thicker !

But there again Petrol is a bit lighter on top!

(With apologizes to Yak!)

Horchsense · Nov 28, 2005

Put couple o' squids of BP unleaded (with light blue nozzle colour) into A4 tdi - on empty tank. Filled rest of tank with £50 of diesel. Drove home no probs - phoned RAC - they said don't worry. Phoned Audi - they said "it will invalidate your warranty - have the car transported in immediately". Even a tiny amount of petrol will dilute the engine lubricants that are vital to high pressure Diesel systems.

It was common practice in old fashioned Diesel engines to dilute the fuel with petrol in the winter - some lorry drivers used to light a fire beneath the fuel tanks to "thin" the fuel. But modern direct injection systems are not the same.

Phoned RAC who obliged with low-loader. Service manager told me that BP had recently appeared on Watchdog - 'cos "lots of people had put light blue nozzle in Diesel tank" - (Light blue is Esso Diesel 2000 colour I think)...Phoned BP customer services - they refunded £150 (Audi dealer labour charge) for draining tank plus £50 worth of Diesel. Moral? RTFM maybe - or at least the pump...

marriedblonde · Nov 29, 2005

Do you really need to read the manual to know that you should put diesel in a diesel car and petrol in a petrol car...

Do you have little notes on all the knives in your house "Do not stick into leg" /ubbthreads/images/graemlins/laugh.gif

d3fy · Nov 29, 2005

I have not had a oil burning in 5 years but for some reason I always double check the nozzle before it goes in, always.

marriedblonde · Nov 29, 2005

I went to fill the wifes car up sunday night and had to check three times before I pulled the trigger!

Horchsense · Nov 29, 2005

[ QUOTE ]

Do you have little notes on all the knives in your house "Do not stick into leg" /ubbthreads/images/graemlins/laugh.gif

[/ QUOTE ]

Man goes to the doctor with knife & fork marks on his forehead - doctor says "you're not eating properly" (apologies)...

Colour coding can be confusing - Diesel usually black - but often yellow - Esso light blue, BP navy blue etc. We're all human - easily done if you're tired stressed etc...BP accepted their responsibility for creating confusion and paid up...

alan braine · Feb 4, 2014

iv just put a tenners worth of petrol in my a3 diesel and toped up with 58quids worth of diesel and drove home do you think things will be ok

sliced · Feb 4, 2014

alan braine said:
iv just put a tenners worth of petrol in my a3 diesel and toped up with 58quids worth of diesel and drove home do you think things will be ok

39586d1347941702-my-tea-lasers-moved-not-dead-yet-long-shot-holy-batman-thread-resurection.jpg

mjr901 · Feb 4, 2014

alan braine said:
iv just put a tenners worth of petrol in my a3 diesel and toped up with 58quids worth of diesel and drove home do you think things will be ok

I used to work for a petrol station, happens all of the time,

It won't even notice mate at those ratios.

Just fill again at 3/4 and 1/2 to be sure it dilutes.

DriverN00B · Feb 4, 2014

From the sounds of the thread, the diesel will have sunk to the bottom and the petrol will be at top. So when your tank runs low, it could cause issues as a tenner is quite a bit if it hasn't just diluted and mixed. Personally I'd get it drained from a garage.

DriverN00B · Feb 4, 2014

mjr901 said:
I used to work for a petrol station, happens all of the time,

It won't even notice mate at those ratios.

Just fill again at 3/4 and 1/2 to be sure it dilutes.

That'll do the trick, refilling and making sure it does mix! Good little trick thanks.

alan braine · Feb 4, 2014

thanks for the advice fingers x and i will just keep toppin it up will keep yea posted

Andy Crooks · Feb 4, 2014

A small amount of petrol can go into diesel but diesel can't go into a petrol

Sayam · Feb 5, 2014

If it was my car I wouldn't worry at all with £10 petrol and tank full of diesel. I'd just drive it...

Boon · Feb 6, 2014

Diesels will run on pretty much anything liquid and burn-able. Petrol will dry out the seals in pumps but not at quantities said above

Fill up with derv and all will be fine (a tiny bit of mineral 2 stroke oil will help with lubrication too

)

Alex_007 · Feb 8, 2014

I put over half a tank of unleaded in my tdi and it didn't make any difference , still ran ok .

Jake Sanders · May 27, 2017

I know this is a bit late but recently my wife put a couple of litres of wrong fuel into our Audi A3 1.9 TDI. After calling a couple of people and trawling through different threads we came across this site (http://www.wrong-fuel-in-car.co.uk/) which basically asked us for some information and it gave us feedback. Our vehicle luckily was mostly filled already so we didn't need to get an engineer out to fix it, but I thought it was a very useful thing to have used, definitely eased my mind!

desertstorm · May 27, 2017

With the 1.9 TDI it's not much of an issue filling with Petrol as they use seperate pump injectors which aren't so affected by the lack of lubrication from running petrol instead of diesel. More modern common rail diesels where the pump is entirely lubricated by the diesel do not fair well if run with a high percentage of petrol in. As already stated in a lot of Scandanavia and colder eastern european countries they add petrol to diesel to winterise it.
Small amounts are not an issue.

audismart · May 27, 2017

h5djr said:
Probably. My brother drives a diesel VW Polo and a few months ago had a mental block and filled his tank with unleaded petrol by mistake.

He phoned the AA and they said that, providing he had some diesel left in the tank when he filled up the petrol would sit on top of the diesel as it's much lighter. They suggested he drive home gently ( it was a Sunday) and in the morning get a garage to drain the tank and flush it out and refil it with the correct diesel and everything should be OK. It was and he had no further problems.

Putting diesel into a petrol car is more of a problem as it sinks to the bottom of the tank straight away.

As he had only put a small amont of petrol in he would not had to much of a problem, but it would have been a good idea to try and syphon the petrol off the top of the diesel at some stage.

Considering petrol is pulled from oil and diesel is left as a by product, I`m not so sure this statement can be true??? It will mix but the diesel will loose some of its lubricity.

What effect would 1.2 litres of petrol have on a diesel engine?

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