Put Petrol in a Diesel Subaru Forester by Mistake?
We'd urge you to keep your motor off if you've put petrol in a diesel Subaru Forester and not run it yet, and that counts for shifting it off the forecourt as well. A fuel drain is generally sufficient to set the Forester right, provided that petrol stays inside the tank, which it does whilst the motor is off.
We go to misfuelled vehicles instead of the other way round, so with Petrol in Diesel your Subaru Forester remains at the forecourt or wherever it has stopped. Call us before you try anything yourself and we will talk you through it.
Put petrol in a diesel Forester? First steps
- With petrol inside the tank, a diesel Forester will generally still start and run, and feel completely ordinary for some miles. That's why people frequently drive off without spotting a problem, and why your motor needs to be left off.
- Turning your ignition on is all it takes, on a lot of diesels, to start the fuel pump priming and draw fuel from the tank to the injectors, so keep that off too.
- Topping up with diesel to thin it is a bad idea, even with super unleaded, which is petrol too. The tank on the Forester takes up to 64 litres, and each litre of diesel put in is more contaminated fuel for us to empty.
- If the vehicle is in the way of a pump, pop it in neutral and push it clear. Forecourt attendants are generally glad to help with that.
- Call 0333 366 0103 and let us know which Forester you have and where it is, roughly how much petrol was put in, and whether the engine has been started. If the exact variant is shown on the badging, say the Forester 2.0D, give us that as well.
What running your motor does with wrong fuel in your Subaru Forester
Turning on the engine is what draws the wrong fuel in your Subaru Forester out of your tank, and only then does it start to reach the engine. Whilst it passes through, diesel fuel keeps the high-pressure fuel pump and the injectors oiled, and the motor depends on that. That protection is washed away as soon as petrol thins your diesel, so the damage, where there is any, is down to driving on that mix.
If you've driven the Forester on it, the thing to do is stop somewhere safe then switch your motor off. We drain the tank, then rinse the pipes and filter through until no tainted fuel is left, so it can still be put right. Lasting damage is very unusual if it is caught soon and given a proper clean.
The Subaru Forester fuel tank capacity, version by version
What counts is how much of your fuel in your tank is petrol. The same couple of litres count for more when you fuelled up with the tank close to empty, which is why its size makes a difference.
In our figures, all the diesel variants of the Subaru Forester use one tank of 64 litres, so the calculation comes out the same for every one.
Which diesel version of the Forester do you drive?
It is useful for us to have the version when you ring, and it's generally on a badge at the rear of your car.
AdBlue in a diesel Subaru Forester by accident
Some diesel vehicles carry a mix of water and urea, called AdBlue, in a tank of its own with a dedicated filler, and use it to clean up their exhaust. If you have AdBlue in a diesel Subaru Forester because it went into the wrong filler, don't turn the key, even to shift your car.
AdBlue settles to the base of your tank, where your pump pulls its fuel from, as it won't mix with diesel. Being mostly water, it cannot ignite and leaves the fuel pump without lubrication, and the diesel in a tank holding up to 64 litres doesn't weaken it the way it would petrol.
Even a little gets drawn into your fuel line. Deposits of urea build up in your filter, your injectors and the rest of the system as the water evaporates, and they attack the metal they sit against.
Check under your fuel flap if the Forester has an AdBlue filler, since on plenty of vehicles it is right beside the diesel filler. You can usually tell the AdBlue lid by its blue colour and the far smaller nozzle it fits.
What we do in a fuel drain on your Subaru Forester
A fuel drain on your Subaru Forester is done beside your vehicle, so it doesn't need to go to a garage. We start by confirming what went in and whether the engine has run, then drain your tank, which on the Forester takes up to 64 litres. After that we flush the fuel pipes and the fuel filter and fill up with clean diesel, and the fuel system is primed before we start it.
You can drive the Forester away once the job is done, running on fresh diesel.
AdBlue removal from a diesel Subaru Forester
We take the same steps for AdBlue removal from a diesel Subaru Forester as we do for clearing petrol. Since AdBlue doesn't blend in but collects at the bottom of the tank, running the Forester on it can leave crystals inside the pipes. Those get flushed through as well, and the filter is changed where needed.
AdBlue removal here means taking AdBlue out of your diesel tank once it has gone in the wrong filler. It doesn't mean taking out or disabling the AdBlue system on your vehicle.
A fuel drain on the Subaru Forester: the cost
We do not publish a fixed quote, because the work changes from one job to the next. These are the main factors that change it:
- most of all, whether the Forester has been driven or even started
- the volume put in, weighed against the size of the tank
- whether it was AdBlue rather than petrol
- the location of the Forester and how easily we can reach it with the van
We can let you know what this work will probably involve when you ring and give us those answers.
Questions about petrol in a diesel Subaru Forester
Do you know the fuel tank capacity of the Subaru Forester?
It holds 64 litres, and our data show the same tank on each version.
I just put a little petrol in my Forester. Should I top up with diesel?
We wouldn't recommend it. Putting in diesel lowers the share of petrol without taking out any of it, so the petrol is still in your system when you drive off. All of it is removed with a fuel drain, which for a modest quantity is usually everything your Forester needs.
Should my Forester go to the Subaru dealer?
No. We're independent and have no tie with Subaru or its dealers, plus we drain and clean your Forester wherever it is parked, so there is no need to move it anywhere.
Am I insured for wrong fuel in my Subaru Forester?
It's worth looking at your policy, as misfuelling cover is included in some but not all. Whatever it says, we come out and empty your car.
What if I put diesel in the AdBlue tank of my Forester?
Keep the key out of your ignition in that case as well. Limp mode and a warning are what most motors give you when they are driven like that, and their AdBlue system will need emptying. Which tank the fuel was put in is worth telling us when you phone.
What should I do if I've already driven my Forester?
Look for a safe spot to pull over, then turn the motor off and leave the car that way till we get there. Wherever you have pulled over, the fuel system is drained and cleaned there, and caught early like this, it very seldom leaves permanent damage.