SLROC Forum

Hey guys, i have a mate who has a Defender with a 300 Tdi...... i think. He told me other day that alot of people put some petrol in diesel tanks to help with starting and running in really cold temperatures. I personally believe this to be complete bollocks but he said he researched it and went ahead and stuck a tenner of petrol into a nearly full tank of diesel. He is now having some running problems! Is it likely to be the petrol thing?

My folks are running a 90 tdi and it is having no trouble starting in the current temperatures!

Any thoughts?

Cheers
Ally

Atenners worth is probably too much, maybe a litre per tank,but not for TD4 or TD5

check the glowplugs

Geoff

ok, i had never heard of putting petrol in a diesel was all, ill tell him the glow plugs idea, cheers guys.

There used to be a big problem with diesel fuel "waxing" in cold weather and blocking fuel pipes. Drivers would add paraffin, petrol, kerosene, alcohol or such like to reduce the freezing point of the fuel. Too much would however defeat the inherent lubricating properties of diesel that was needed in the pumps of those days.

Now the fuel is more complex and the refinery uses additives to overcome the lack of sulphur, and to reduce the waxing at the temperatures we have been having. So no point in adding more, unless the fuel had been purchased in the summer when the anti-waxing chemicals are not being added, or you are experiencing temperatures below -20C.

Yes Petrol in a diesel tank will reduce the chances of the diesel from waxing in very low temperatures.  The diesel we buy in the UK in winter will typically work trouble free (wax free) to about -12oC  as additives are added at the refinery in the winter.  Cars with pre heaters will work to an even lower temperature.  As for the physics, a 1:50 mix is generally regarded as the right mix, any more and you run the risk of damaging the injectors pump.

I concur Archi, -10 to -12 is the waxing point for diesel

ave had no probs with ma 110 300tdi starts first time and its been cold here in penicuik i have heard of people running with veg/bio fuel that they have to winterise the fuel approx 5% with petrol to stop waxing up durring the cold weather

MY 300 TDI started no bother no waxing at -17 I came home from work  it was all defrosred (caravan heater in it and took it for a run) yes after out in taxi for 12 hours thought lets drive    4am by 10am it was zero and blizzard and i missed it in bed

Aww unlucky mate, I was out last night doing doughnuts on the driveway in the disco...... to get the snow off the roof then a late night drive

Hi
 Petrol in a modern diesel is NOT A GOOD IDEA. Older type diesels  had fuel injection equipment which in some cases had a separate lubrication facility. Modern diesels depend on the fuel providing the lubrication for the various moving parts. I have known of a number of instances of 200/300TDI fuel pumps seizing up when when petrol was accidentally put in. The recommended procedure in such cases is not to even start the engine but to drain the fuel system, flush with diesel and refill with fresh fuel. I have known of fuel injection pumps to seize and strip the timing belt on these engines. The same applies to BMW and other modern diesel engines. I am aware of people who have taken the chance by diluting the fuel ie add more diesel, and getting away with it. I would suggest that to try such on a TD5 would be madness. Petrol has no lubricating properties so serious damage would result.
 The days of putting paraffin in etc are long gone!

 Regards

if you do go down this route with your landie remember and stick a little 2 stroke oil through your tank after the winter to lub up your injection pump, 2 gallons of petrol is way too much half a gallon a tank(a wee tank that is) is about as much as would go, td5 can take kerosene no probs, Tio