What Happens When Fuel Goes Bad: A Guide for Subaru Owners

What Happens When Fuel Goes Bad: A Guide for Subaru Owners
May 4, 2023 City Subaru
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Left your car sitting in the garage for a few months? Maybe you were on vacation and have come home and are eager to restart daily routines – like driving to the petrol station on your way to work.

You might well be wondering – can fuel go stale over time and if so, what can bad fuel do to your car? Fuel quality plays a significant role in your car’s performance, and contaminated gas can cause a variety of problems.

It’s true that fuel can go bad over time – and can even have negative effects on your engine and internal components. So before you start up that engine, read on to find out what bad fuel can do to your car and how to avoid fuel contamination.

What is bad fuel?

Bad fuel is petrol (or diesel) that has been left in the gas tank without being used for lengthy periods. The fuel quality can deteriorate due to factors such as water contamination or exposure to extreme heat, leading to contaminated gas.

The lifespan of your tank of fuel will depend on various factors – including your surrounding environment – level of heat and sun exposure. You may find that after a few months, most of your fuel has evaporated due to high temperatures. Heat waves are common throughout Australia, so this can also be an exacerbating factor.

What can bad fuel do to your car?

When fuel goes stale, over time, its chemical composition changes. This has several effects on your vehicle, especially in extreme cases.
For starters, stale fuel pumping through your engine can corrode your engine and fuel injectors and fuel filters. This can have wide-reaching effects on your vehicle’s performance. Let’s take a closer look at the symptoms.

what can bad fuel do to your car, What Happens When Fuel Goes Bad: A Guide for Subaru Owners

Warning signs to look out for

If any of these warning signs show up – get your car down to the nearest Subaru repair shop:

Check engine light shows up

Often the first sign will be your engine light on the dashboard – this should light up if you have a problem with your engine.

Reduced performance

Bad fuel can result in your engine and fuel system doing strange things, like trouble starting up, producing a rough-sounding idle, or stalling during acceleration. These problems could be due to water content, low octane, or the wrong fuel type.

Fuel is darker and more like sludge

If you get a chance to examine the fuel – by syphoning it out from your tank with a fuel line and notice that it is significantly darker and muddier, this is a sign that your fuel has gone bad. Fresh gas should be clear and free of water contamination.

What to do when fuel goes bad?

Bad fuel can have a variety of negative effects on your Subaru engine. That’s why it’s essential to bring your vehicle to a qualified Subaru dealer straight away to drain out the bad fuel. If you can, get it towed to avoid any potential further damage to your engine. By removing the fuel from your gas tank, pump and engine Subaru technicians can replace the old with fresh gas and get your vehicle up and running again.

How to avoid fuel going bad

Don’t worry – there are multiple ways to avoid the worst from happening. Here’s how:

Fill up with high-quality fuel

Filling up at the petrol station with the proper fuel type for your vehicle is essential in maintaining your engine’s integrity. Choosing premium fuel over regular gas can help ensure proper combustion and prevent fuel contamination. If you want to learn more about which fuel type is right for your Subaru model, check out our blog here.

Add fuel stabiliser and fuel additives

If you know in advance that your vehicle will go un-driven for a long period, you can always plan ahead to avoid any troubles with your fuel tank when you return. By adding fuel stabiliser and fuel additives to your tank, you can extend your unused fuel life by up to 12 months and maintain fuel quality.

Drive more often

It sounds simple but simply drive more regularly. By using fuel in your car more regularly, you avoid the possibility that it will go stale. If you do leave it for a month or two, you can always refill it by a third to re-invigorate the existing fuel.

Keep up regular services

This cannot be overstated: regular servicing at your local Subaru dealership or service station can help target issues before they come to bite. Remember to keep your service logs to track your car’s performance and repairs.

what can bad fuel do to your car, What Happens When Fuel Goes Bad: A Guide for Subaru Owners

Cost of repairs for vehicles affected by bad fuel

Luckily, repairs for vehicles affected by bad fuel are not as high as a gearbox change. With the right equipment, Subaru technicians can drain and replace fuel quite effectively without causing any further damage to the engine. That being said, if you have driven on bad gas for a while already, there may be other engine parts that might need replacing – thus adding to the cost of the repair bill.

 Why consult a certified Subaru technician?

It’s important to consult a certified Subaru technician for all of your vehicle’s maintenance and repair needs. Certified Subaru technicians are trained and certified by Subaru to work specifically on Subaru vehicles. They have extensive knowledge of the unique features and components of Subaru vehicles and are equipped with specialised tools and equipment to diagnose and repair any issues. Choosing a certified Subaru technician ensures that your vehicle is in the hands of an expert who understands the intricacies of your car and can provide the highest quality service – while also maintaining your vehicle’s warranty.

what can bad fuel do to your car, What Happens When Fuel Goes Bad: A Guide for Subaru Owners

Book your Subaru for a service today

Whether you’re concerned about the effects of contaminated fuel in your Subaru or require a service, get in contact with the experts here at City Subaru. Our friendly team is ready to assist you with any issues you might have, from fuel gauge problems to water content in your fuel.
Drive with confidence this season and book your City Subaru service online or just give us a call at 08 9468 8491.


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