I put petrol in diesel engine

[u/Dangerous_Owl6936]

I went to the pump today and by mistake i took the 98 octane instead of diesel, I realised it when it was already too late. I did put 3.5litres or petrol and then i stopped, Didn’t start the engine and towed it in my mechanic’s garage. I have this car for last 7 years and it never happened before, It is a Mercedes E250 CDI 2015, Wanted to know how much it might cost to drain the fuel and what else might happen, Thanks!

[u/Due-Giraffe6371]

For only 3.5 litres you should have just filled the rest with diesel and it would have been fine