BMWs are often known to be expensive cars. Not only are they more expensive to purchase, but also to run and maintain.
But one of the most common questions prospective new owners have is around which fuel to use.
So, do BMWs need premium gas?
BMW recommends that owners only use premium unleaded gasoline to maintain optimal performance and to preserve the longevity of the engine. For some models this is only a recommendation, but for others it’s a requirement.
Those who have been driving BMWs for a long time may be accustomed to filling up with premium-grade fuel, but for new owners this may come as a surprise.
But is there any way around this, and what happens if you accidentally fill up with regular fuel?
BMW fuel requirements
High-grade fuel with an octane of over 91 is recommended for all BMWs. Gasoline with an octane rating of below 91 should not be used. The higher the octane, the better it is for the car’s engine.
BMW makes these recommendations with the best interest of the car’s health in mind. Although it may be more expensive to fill up with premium gas, it will be cheaper in the long-run as your car is likely to last longer and suffer from fewer issues.
It’s important to note that fuel ratings differ between North America and other parts of the world, such as Europe and Australia, as these regions use RON (research octane number) as the measure.
91 octane in the US is equivalent to around 95 RON in Europe, and 95 RON is often classed as regular unleaded in that region.
Do you have to put 91 in a BMW?
BMW makes it clear that the octane rating of the fuel should be above 91, and although you don’t have to follow this recommendation, it’s wise to do so for the sake of your car’s engine.
Ultimately, once you’ve bought the car it’s your choice as to which fuel you fill up with. But BMW does not make this recommendation without reason, so it’s a good idea to follow the manufacturer’s advice.
Many BMW owners choose to ignore the advice and fill up with regular 87 octane as it’s cheaper, but this is unwise and is likely to be a false economy in the long-run.
There are a number of problems that can occur if you don’t use 91 octane or above…
What happens if you don’t put premium gas in a BMW?
The car won’t be operating at its optimal temperature and its performance will suffer as a result. It’s also more likely to suffer prematurely from engine problems thanks to the additional stress it’s placed under.
There are many reasons that BMW’s engineers suggest using premium gas, but ultimately they all boil down to preserving two things; performance and longevity.
By not using premium gas, you will not be getting the most out of your engine and may find yourself out of pocket when the time comes to get it serviced.
You will also lose some of the car’s performance, and performance is often the reason people buy BMWs in the first place.
Can you use regular gas in a BMW?
You can use regular gas in a BMW, but you shouldn’t if you want to prolong the life of the car and avoid paying out on costly engine repairs.
One of the key issues with using regular gas is that it’s more likely to lead to a build-up of carbon deposits within the engine, which only gets worse over time.
Cars that are recommended to use premium gas often have high-compression engines. These engines are particularly susceptible not only to carbon deposits, but also to temperature fluctuations.
When you combine these aspects, it’s easy to see why using regular fuel in a BMW for prolonged periods of time is likely to be a costly mistake.
What if you accidentally put regular gas in a BMW?
Using regular gas accidentally won’t do any lasting damage to a BMW; the car’s onboard computer will adjust the timing to compensate. Simply fill up with premium fuel next time you’re at the pump.
Using gas below 91 octane as a one-off shouldn’t be a problem for your engine, but avoid driving aggressively until you’ve filled up again with premium to reduce the risk of any damage occuring.
It’s a common mistake, and is sometimes unavoidable if there is no premium-grade fuel available at the gas station you’ve stopped at.
If you’re concerned, you can fill up with premium fuel once you’ve reached half a tank rather than waiting until you’re empty. It’s absolutely fine for the two grades of fuel to mix. They will combine to form an octane somewhere inbetween.
Which BMWs are required to use premium fuel?
All BMW M cars and all BMWs built prior to 1997 are required to use premium fuel. Those with high-compression engines should also only use 91+ octane gasoline.
BMW M cars are always fitted with high-performance engines which absolutely must use the best fuels, lubricants, and other consumables to perform at their maximum and protect them from lasting damage.
It goes without saying that these cars should always use the highest quality fuel available.
Older BMWs and those with high-compression engines, such as turbocharged models, should also be using premium fuel at all times. BMW make it clear that in these scenarios premium fuel is a must.
For all other BMWs, premium gas is only a recommendation rather than a requirement. But we’d stick with premium regardless.
Here at The Car Investor we own two BMWs; a 1996 840Ci and a 2007 M5. We run both of these cars on premium fuel at all times.
Despite it being more expensive at the pump, we take comfort from the knowledge that we’re doing everything we can to protect our engines for the future.
If you own a BMW and are in any doubt as to which fuel you should use, you should check the owner’s manual or the sticker underneath the fuel filler cap. Make sure you stick to BMW’s recommendations and there will be nothing to worry about.