A little diesel in my petrol tank

[spiff]

I was distracted this evening and accidentally put about 600ml of diesel in my fuel tank. There was around 10l of 98RON in the tank before my error and after I discovered my mistake, I continued to fill up 43l of 98RON and drove about 4km home. I've read the threads of diesel owners having problems and big bills. A preliminary search on google shows a little bit of diesel won't cause too much harm to petrol engines.

Just wondering if any experts or experienced people can weigh in on this.

[vdubmotorworx]

Will be fine mate...600ml is nothing but i would run this tank down to half way then fill again just to dilute it down.....and then your back to normal. The people with big bills are owners of common rail diesels that put a tank of petrol in and drive until it stops! Dont worry you will be fine....VDUB...

[brad]

You'll be fine.

I once ran my VK Commodore on a 50:50 mix of diesel & petrol. It wouldn't idle & blew a lot of smoke but there weren't any lasting issues. I'll admit that a VK Commodore is fairly agricultural & can probably can take a lot more abuse than a VW though.

[spiff]

Good to hear. Thanks for the tip about diluting. I'll do that.

[bluey]

How does one do that?? All the diesel pumps I have seen have the mechanical lockout to get the nozzle out.

[Guest001]

How does one do that?? All the diesel pumps I have seen have the mechanical lockout to get the nozzle out.

Not all do unfortunately. Had one Caltex one last Saturday that just went when i pulled the trigger. Pulled straight off the bowser as well.

[wai]

The thing though is that even the low flow diesel nozzles are too large for the restrictor in a car designed for ULP.

That said, the reason diesel engined vehicles have costly repairs is two fold.

The first is that diesel acts as a lubricant for the high pressure fuel pumps in common rail diesels. Petrol simply has nowhere near the same lubricating properties.

The second is that the compression ratio in a diesel is at least double that of a petrol engine, and this causes detonation and other unwanted consequences of using petrol in a diesel.

[Umai Naa!!]

Nozzle restrictor was written out of the ADRs back in '08 from memory, off the back of banning Super (leaded) fuel.

As the others have said, a small amount of diesel in a petrol car won't bother it too much. Might notice a little smoke, but that'd be it.

[gldgti]

The second is that the compression ratio in a diesel is at least double that of a petrol engine, and this causes detonation and other unwanted consequences of using petrol in a diesel.

Not really, diesel is injected at the point at which you want fuel to ignite anyway, and not before. it literally combusts as it is injected because the temperature and pressure in the cylinder is already higher than the autoignition conditions. Since the fuel isnt just in there to start with like a petrol engine, thats not the problem. The big one is that it doesnt lubricate well and that the peak cylinder pressures and temperatures are very high.

You can tune a diesel engine to run on just about any combustible liquid if you have a robust enough injection system.

[bluey]

I thought the big one was the lack of lubrication to the high pressure fuel pump. There are a large number of cases in the USA of premature failure of the HPFP, causing rather expensive to repair metal particle contamination of the injection system. It is thought that a signifcant chunk of these (maybe half) could be attributed to single incidents of misfuelling with petrol. The HPFP runs at high mechanical load with plain bearings for the cam roller. It it thought that short periods of no lubrication are enough to cause bearing damage which proceeds to complete bearing failure and there are no filters between the HPFP cam and bearings and the common rail.

NHTSA investigation is ongoing.

The RACQ published an info sheet on misfuelling (2014):
"Older style diesel engines may tolerate a small amount of petrol mixed with diesel without too much damage, although this is definitely not recommended. However newer Common Rail diesel fuel systems are far less tolerant of the wrong fuel and any level of petrol risks damage, as the high-pressure pumping elements rely on the lubrication properties of the diesel fuel. Petrol is a solvent which strips away the diesel fuel from the highly loaded pumping elements causing catastrophic damage."

Are there any reports of other types of engine damage caused by misfuelling apart from HPFP failure??