Wrong Fuel

Roger Brownlee

New member
Joined
Dec 14, 2020
Messages
3
I put about 5 litres of diesel in my mark7 Golf 1.5 tsi on top of a full tank of petrol. In spite of what I have read it has been running fine with no problems.
However, as a precaution I had the fuel professionally removed and the fuel lines cleared. A full tank of full has since been added and the car is fine.
The only negative is that a couple of times a sign has flashed up telling me to reduce oil level. The dip stick is showing too much oil so I am somewhat mystified? Should I have the oil drained and replaced as well as the oil filter? I hope I have not done any damage to the engine.
 

Crasher

Administrator
Staff member
Joined
Apr 22, 2006
Messages
26,690
Location
Nottingham, England
I can't think of a correlation between Diesel in the tank and the oil level going up, could you message me the reg so I can ponder over the workshop manual? What mystifies me is how you put Diesel in a petrol car, the design of the nozzle and tank neck are supposed to make this impossible. When did the car last have an oil change? Running it like it is could damage the emissions side, i.e. cat and exhaust sensors but a slight overfill or dilution should not affect the mechanical side.
 

Roger Brownlee

New member
Joined
Dec 14, 2020
Messages
3
Thanks for replying Crasher, the reg for the car is Y123JMB JMB, although originally AX19FFJ. Car first registered in7/3/19.
It this a 1.5TSI GT spec and has done 9500 miles with an oil change about 1k in August.
Previous Golf a TDI and distracted during fuelling early in the morning. Not concentrating- no excuse really!
Would it make sense to book car in with local main dealer and have a health check?
They could drain the oil, change the fuel filter and check the emissions side. I hope it’s not the catalyst, expensive to replace from what I hear. The mystery is the car runs to well with no hesitation or misfiring.
 

Crasher

Administrator
Staff member
Joined
Apr 22, 2006
Messages
26,690
Location
Nottingham, England
The cat can usually be cleaned by someone like DPF clean team, it is getting oil out of the silencers that is the problem. I can’t see any info on fuel in the oil or any clue as to why in the VAG system.
 
Last edited:

Roger Brownlee

New member
Joined
Dec 14, 2020
Messages
3
The cat can usually be cleaned by someone like DPF clean team, it is getting oil out of the silencers that is the problem. I can see any info an fuel in the oil or any clue as to why.
Our local Vw dealership did a health check yesterday and all ok with car. I suspect they overfilled the oil when car was serviced only 1k miles ago and when I pressed them they admitted they had siphoned some of the oil out! Also if I had any ongoing problems it would be down to the garage and to bring the car straight back to them. Perhaps all an unnecessary worry
Any thanks for your response and help.
 

Surfeit

Member
Joined
Sep 19, 2015
Messages
55
My wife has done something similar in her one liter polo. £20 of diesel into the petrol tank on top of minimal residual fuel (just above red line).

Didn't notice the mistake and drove it the 1 mile home. Next day drove it one mile to the shops without incident but started running rough on the return journey. So 3 miles in all with diesel in the tank and of course the engine will now not start at all.

She is angry with herself. Told her it's not an uncommon situation.

She recalled that the nozzle in the filler seemed strange. The smell from the filler corroborates misfueling. She doesn't have that green insert that stops the diesel nozzle fitting into the aperture.

YouTube shows a video of a guy removing, flushing and cleaning the tank, fuel rail and injectors and then blowing the lines through.

Looking at a professional service to do this rather than DIY. Too much fuel and faff.

But the Cat might be an issue too.

We'll see.
 

Crasher

Administrator
Staff member
Joined
Apr 22, 2006
Messages
26,690
Location
Nottingham, England
Technically it is supposed to be impossible (it is a legal requirement under type and use regulations) to put a Diesel into a post 1992 petrol engined car in Europe as the big Diesel nozzle will not fit in the neck which has a restricter that is built in and not removable. Yes putting petrol in a Diesel is common, but not the other way around. However I have had two instances of Diesel in petrol recently and both customers could not figure out how they did it and neither got a receipt, did your wife get a receipt? With the Fuel of the Devil emptied from the tank and some fresh petrol put in, the technique is to cycle the ignition multiple times or use a diagnostic system to run the pump and with the fuel return line at the tank disconnected (into a can) eventually the system will be flushed clean engough that eventually it will go and then stick a full tank on top and see what happens, in the two cases I dealt with there was no knock on effect.
 

Surfeit

Member
Joined
Sep 19, 2015
Messages
55
Crasher. Thanks for your reply.

I'll post a report once it's sorted. No receipt unfortunately. The more she thinks on the event the surer she is that it was diesel.

Best wishes.
 

Surfeit

Member
Joined
Sep 19, 2015
Messages
55
£100. Which includes the £20 of petrol he put in. Removed the lift pump. Emptied and cleaned the tank and blew the lines through. New fuel put in the tank and with a cough and a splutter it started.
 
Top