Diesel in petrol symptoms

So your wondering if you have put diesel in your petrol car.

Here is a list of symptoms.

Too cheap, yep gone are the days when diesel was cheaper than petrol, diesel commands around a 5p premium over petrol so if your “diesel” was the same price as petrol you have your answer!

After filling your diesel with petrol it will always start totally  fine (still has clean fuel in system from when you arived to fill up), however depending on the ratio of the mix and your cars specific fuel system type, and your style of driving, trouble will not be far away.

Typical scenarios I see every day, would be 60 litres of petrol in a range rover diesel, (100 litre tank) the tank had 40 litres in it and is now just over half petrol, the range rover starts no problem and pulls away like it should, when pulling out of the petrol station on the main road it suddenly looses power and the stops responding, the engine slows down to an idle then cuts out, when attempting to restart it – it will seem to want to go but never catches properly,

A diesel trying to run on petrol never does well, some people mistakenly eliminate misfuelling as the cause of concern because they drove for …. so many yards/miles after leaving the petrol station without any problems, to understand this you have to have an idea of how a cars fuel system works.

The typical fuel system will hold between a litre and 2 litres of fuel, in the pipes and pumps of the car, when you first start after misfueling this is what you car will be running on, this very rapidly will go from being 100% diesel to whatever is the ratio of wrong fuel that has been pumped in, the symptom of this happening is a sudden loss of power.

Your car will refuse to re-start after it has broken down after a misfuel, don’t worry too much about this – it’s not a indicator of engine damage, its simply the matter of having the wrong type of fuel in.

If you are unsure if you have put petrol in your diesel, check your receipt if you can, if you dont have one you can always ask the petrol station to check the cctv cameras of when you filled up, they always keep the tapes – and a friendly garage will  be happy to help.

Then, you can have a sniff, just open the filler cap and catch a waft, petrol is petrol, and diesel is diesel, they have distinctive and separate smells, pure diesel will never smell “a bit” like petrol, it will smell like diesel, so if you diesel smells a bit off, chances are it has petrol in it.

If you take a car to a main dealership with a petrol in diesel problem they will most likely send off a sample to get tested, this costs about £130 pounds and only a test tube amount is needed, this provides a full analysis of the fuel, which also checks for water & other contaminates, the tests are very accurate and are used in determining liability should a misfuel be the cause of damage.

These tests are available to the general public for a fee, and it might surprise you how often they are done, cars coming off lease, fleet maintenance companies, hire purchase companies, and  hire car company are all known to regularly fuel test vehicles and are not slow to pass on massive repair bills to the unlucky client who put the wrong fuel in.

I know of  main dealers that fuel test every high value trade in and will reduce the purchase price of the trade in by thousands if a previous misfuel is detected (these tests are VERY accurate and can detect tiny quantities long after the misfuel occurred)

It is not uncommon that a car will go for hundreds of miles after a misfuel, but will refuse to start again from cold, there is a simple explanation for this, when your engine is hot it can tolerate a much higher mix of petrol in diesel than when it is cold, so if you fill up with the wrong fuel and your car is running normally (albeit slightly underpowerd) you have not necessarily gotten away with it – chances are it will not restart.

Many people reading this will have put the wrong fuel in and made it home, they may be wondering what happens next, well, the chances are when you go out tomorrow morning to start your car.. you will be calling a fuel technician and it just so happens I know a very good one!




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