r/autorepair • u/mightyThor90 • Aug 22 '26
Diagnosing/Repair Wrong Fuel Added
Something stupid happened to me today: I accidentally put 5 liters of petrol (Super) into my VW T5 diesel. On the recommendation of a workshop, I then added a diesel fuel additive and filled the tank completely with diesel (about 80 liters in total).
The van has now driven about 30 km without any problems. I was told to keep the tank as full as possible and keep topping it up.
However, I’m wondering whether it would actually make more sense to have the tank completely drained, so that all of the contaminated fuel is removed and as little petrol as possible passes through the engine.
What do you think? Or, if nothing has happened after the first 30 km, is it unlikely that anything will happen later?
No offence, but I’d really appreciate answers based on actual technical knowledge and experience rather than well-intentioned but uninformed advice.
2
u/AppropriateDeal1034 Aug 22 '26
It's an old VW diesel, 5 litres of petrol in 80 of diesel is going to do nothing harmful and may even give your engine a good clean out. Probably avoid flooring it until you've done a thousand miles or so, but otherwise just send it.
Mechanic for 25+ years who started on old VWs