I see a lot of strange things in my line of work, and tonight was no different.
A client had filled up with petrol (into his diesel Astra), and realised his mistake, he called a friend who was a “dabbler mechanic” and was told to put 5 litres of engine oil in the tank to “protect the fuel pump”.
The theory of this just about stands up, and it goes like this, petrol is too thin to lubricate the fuel pump, if you put thick engine oil in it will blend with the petrol and raise the viscosity to nearer that of diesel.
Like I said the theory just about stands up, but in practice is unworkable, what happens is the engine oil slides to the bottom of the tank.
Stays there, it then gets drawn into the engine at high concentrations which will only further add to the problems, there are a few “home remedies” for misfuelling.
This one is another unworkable one, allot of this bad advice comes from forums on the net.
Where “someones mates uncles brother once upon a time did blah with a bull nose transit van and it was fine”, the reality is that modern diesel engines are highley tuned and operate on narrow tolerances for fuel they don’t like petrol – and they certainly don’t like straight engine oil!, so If you have misfuelled the best bet is to get it drained any good garage can do it, or any mobile fuel mechanic, if you live in the south east I would be happy to come and do it myself.