How much Petrol can you put in a JTD withou wrecking it?

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How much Petrol can you put in a JTD withou wrecking it?

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The question is how much petrol can you put in a common rail diesel without wrecking it? The latest advice from people like the AA and RAC is that if you put even the smallest amount of petrol in your diesel tank you can’t even turn on the ignition (electric lift pump) without causing thousands of pounds worth of damage.
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They say you must get the tank emptied and the system flushed. Of course they offer this service, at a price. The cost seems to be about £200 plus new fuel. Previous advice was if you put up to about 5 litres (10%) of petrol in your tank, just fill to capacity with diesel and carry on. What’s changed apart from making money draining tanks? Common rail diesel engines like the JTD and mJTD use very high pressures with precision pumps and injectors. These rely on the fuel for lubrication and modern petrol has low lubricity. This can cause galling and wear to pump components, possibly even seizure. The lubricity is provided by molecules that act on the surface of the metal, not a film like conventional oil. Sulphur was a significant provider of lubricity, but has all but been removed from modern fuels.

Back to the question, if I fill the tank of my 1.9l 16V150hp mJTD engined car with 50% petrol/diesel mix what will happen?
Robert G8RPI.
 
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You'd be sent to a doctor to get your head checked out. ;-)

However half of me thinks you've been to a garage and filled the car half way with petrol then realized oh s*** is that where the question stems from? ;-)
 
50/50 mix.. it'll cost you..,;)

If it were me.., I'd tow the car to a safe place, and drain off ALL the fuel..or as much as I could..lift up rear seat - remove pump, syphon from there

I'd happily add a couple of litres of this mix to every subsequent tank fill,

a friend a few years ago did a total fill of petrol in a FORD TD, realised mistake after a 3 mile drive, I syphoned off the @10 Gallons, Ford ran like "normal":eek:, my Uno 1100 ran fine on the diesel tainted petrol.:D

AFAIK the "wrong-fuel" recovery agents let you keep the fuel -as long as you bring fuel-safe containers for it.. my dad got good use of his "Jerry can collection" for the in-laws company car errors..:rolleyes:
 
Well as you may have guessed, I did fill my Croma with unleaded to an almost exact 50% mixture.
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Typical Reason “swiss cheese” incident, not usual filling station (Cornwall), black nozzle on unleaded, stormy weather and distracted by wife asking about shop. Wife also paid which was a chance of spotting it missed. I then drove for 200 miles, mostly motorway 65-70 MPH. The only symptom was missing on over-run down hills. At first I thought this was the very gusty weather. When it was more sheltered there obviously was an issue and I wondered if I'd got dirty fuel or water in the tank (car was parked on a North Cornwallcliff top in a storm overnight). Pulled in at services and checked everything including fuel receipt........
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If I’d spotted it at the time of filling up I’d have done what Varescrazy says, drained the tank and re-filled without starting the engine. At 1/3 tank used and 200 miles run I reckoned any damage was done and I might as well save the de-fuelling fee. I was also still 140 miles from home. So I brimmed the tank with premium diesel and carried on. I later calculated that this brought it down to 30% diesel. I used premium diesel as it generally has better lubricity than standard fuel. The following day I brimmed the tank with premium again bringing it down to 25% unleaded. I also added a diesel treatment that has lubricity additives. I chose Wynns Xtreme diesel clean. This specifically states lubricity improvement and even suggests use after a misfuelling incident. The Millers multi dose treatment also claims lubricity improvement but the common Redex does not. I changed the fuel filter in a couple of days as it was due anyway. Unleaded can affect some rubber seals and plastics so did not want to risk the filter falling apart. Did another 110 miles then topped up again with premium and another bottle of Wynns. This brought it down to 20% unleaded. I then had another long trip to Yorkshire so did 470 miles at 20% unleaded without incident. Having run down to the low warning I’ll use small top-ups to remove the last of the unleaded. Small top-ups work better for this. If you assume 5-6l left in tank and add 10-12l starting at 20% mix, five 12l top-ups (60l) will bring it down to 0.1% unleaded but adding 56l in one go (full tank) gives 1.9% so you are doing more miles at higher concentration of unleaded.
So I ran for 200 miles at 50/50 regular diesel / unleaded petrol mix and 720miles at between 20 and 30 % unleaded to premium diesel in a 1.9 16V mJTD DPF Croma (2006 97,000 miles) without catastrophic failure. No errors on a MES scan either with good pressure demand / measured. It almost certainly increased wear of the pumps / injectors but I’ve seen no change in performance or fuel consumption (it seemed to like 20% unleaded and Wynns mixture
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but I don’t recommend it) so wear may not be significant. I’ve certainly got clean injectors now. From this experience it would seem that if you notice that you are putting petrol in your diesel car and stop before you get to about 10% of the tank quantity (4-6 litres depending on car) you will be OK if you totally fill the tank withdiesel, preferably premium. Adding a lubricity improver like Wynns Xtreme orMillers (NOT Redex) fuel treatment is a good idea. Between 10% and 30% unleaded in diesel I’d recommend draining and clean premium fuel depending on circumstances like age of car, availability of drainage service, distance from home (if you can DIY it later) etc. Over 30%get it drained but you may not notice any immediate effect up 50%.

It seems the tales of instant engine failure at the slightest drop of unleaded in a common rail diesel are exaggerated.
A couple of side notes. Diesel with even a small amount of petrol in it is as inflammable as petrol so handle with care. I’ve also seen advice to add oil to the fuel mixture. This is likely to do more harm than good. As mentioned in the original post, the pumps rely on surface acting lubricity modifiers not an oil film. Normal engine oil will just be dissolved in the fuel but may damage the CAT and block the DPF. Two stroke oil (typically vegetable based) has also been suggested as it is not dissolved in the same way, but it still won’t help the high pressure pump and is more likely to cause damage (two strokes don’t have CATs or DPFs).
Try not to repeat my experiment. With personal and work vehicles I been driving a combination of petrol and diesel vehicles, even same model with different fuel on occasion, for over 30 years. My second car was a diesel Astra back in the early 80's. I've never came closer than putting my hand on the wrong nozzle before this incident.

Robert G8RPI.
 
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at one point we has IDENTICAL Tipo's RED 5 door DGT . same trim,

one 1400 petrol ,
one 1929 TD

I bought stickers for the flaps.. thankfully, no issues.

thought you were going to say the PFS had filled the DERV tank with unleaded.. seen that a few times..!! some VERY smoky petrols until they choked
 
I would not worry !
A few years ago I filled a Citroen C5 with 5k on the clock with petrol and it was near empty to start, after phoning the RAC who wanted £250 to empty and dispose of the fuel. I rang a friend who advised to drive slowly if you hear a pinking sound foot off throttle, as soon as you can add more diesel even if its only a gallon, till you get home, syphon out as much as possible and fill with diesel run the tank as near empty as possible then refill with diesel, back to normal. A friend of mine ran the 20 ltr of contaminated unleaded/diesel through his van no problems.
That C5 went on to 85k miles in 2years no problems what so ever
 
life expectancy for a FRENCH car nowadays:D

Paraffin was supposedly a good diesel substitute, excellent lubricity for toleranced internals.., :)

however it's difficult to find in any quantity AND untaxed.. so technically illegal as a "Fuel":eek:

I have to disagree on the paraffin lubricity. Paraffin (or Kerosine) has very poor lubricity, particuarly the modern "cuts" with reduced sulphur content. The main type of jet engine fuel (Jet A, JP-8) is kerosine based and the fuel pumps and controls have to be designed for it's low lubricity. Whe en refineries reduced sulphur in all fuels many years ago there was a spate of fuel pump failures on some aircraft engines. The US military have worked towards using jet fuel for ground vehicles as well as aircraft to reduce battlefield logistics. The found that they have to either add lubricity modifiers to the fuel or change the fuel system components to use it without excessive wear.
http://www.alu.army.mil/alog/issues/MarApr05/reality.html


Robert G8RPI.
 
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I should've highlighted the "WAS"..,

it was recommended as a thinning( non-waxing) agent for non-winter spec. diesel fuel in winter conditions.. back when I started with diesels around 1993.. A LONG time ago now..,

is Kerosene just another name for Paraffin..or are the constituents a little different.??
 
Paraffin is the UK name, Kerosine is American, but both cover a range of grades. Paraffins are also a specific range of hyrocarbons in chemistry which are not the same thing. Even Jet fuel specifictions don't require an exact composition as long as it meets certain limits and properties it's OK. It's so variable that they use White Spirit (Stoddard Solvent in USA) when testing or calibrating controls and injectors as it is more controlled. (Aviation is my day job).
OK on the "was". When I started with diesel cars in 1983 the pumps were all for trucks with big nozzles and high flow rates. The attendent's would not turn on the pump until you went in and explained that it really was a diesel. The fuel also smelt a lot worse (sulphur compounds again). Adding a bit of petrol in winter to stop waxing made the discussion harder. Paraffin also worked but as noted was not taxed so technically illegal, not that customs were pulling over cars to check for red diesel back then.

Robert G8RPI.
 
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Maximum is 20% petrol. You may notice that your injectors will fail slightly earlier, but this will be the only noticeable damage. Any more will cause damage.
 
Maximum is 20% petrol. You may notice that your injectors will fail slightly earlier, but this will be the only noticeable damage. Any more will cause damage.

20% really - that much.. :eek:

I'd expect pump wear to be an issue before injector issues,
AFAIK the injectors have a level of self calibration. and in the short term a "solvent-flush" may actually be marginally beneficial;)
 
20% really - that much.. :eek:

I'd expect pump wear to be an issue before injector issues,
AFAIK the injectors have a level of self calibration. and in the short term a "solvent-flush" may actually be marginally beneficial;)

20% won't cause any noticeable running issues. You do find that on contaminated engines, that the injector tips will wear prematurely, this will be the first evidence of damage seen - 20% will act,as you say, like a flush and clean them - but is a little harsh though it should not be noticed unless compared to a non-contam vehicle. It would only be 20K difference earlier or similar - neither here nor there really.

Interestingly, those that have diesel LPG conversions actually run at 20% LPG - the max contamination limit.
 
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