Do fuel trucks stir up sediment in underground service station tanks?
QUESTION
Hi John,
I’m always hesitant to fill up my car with Diesel or Petrol after watching the tankers pumping fuel into the main tanks of the servo.
I remember many years ago when I was a young apprentice my boss saying never fill up when you see this as potentially a lot of dirt and water will be stirred and that certainly does your engine little good. In this modern age is there any truth to this?
Many thanks
Gary
AutoExpert DISCOUNT ROADSIDE ASSISTANCE PACKAGE
If you’re sick of paying through the neck for roadside assistance I’ve teamed up with 24/7 to offer AutoExpert readers nationwide roadside assistance from just $69 annually.
Plus there’s NO JOINING FEE. Full details >>
AutoExpert DISCOUNT OLIGHT TORCHES
These flashlights are awesome. I carry the Olight Warrior Mini 2 every day - it’s tiny, robust, and super useful in the field or in the workshop. Olight is a terrific supporter of AutoExpert.
Use the code AEJC for a 12% discount >>
ANSWER
Hey Gary,
Thanks for the great question. This concept doesn’t hold up under scrutiny.
For starters, the de-canting rate of fuel from a tanker to the underground tanks is pretty slow. This is to minimise static electricity, because fuel flowing in a hose generates its own static. So it doesn’t actually churn up the fuel already in the tank.
Water doesn’t mix with liquid fuels. So any condensation which might (unlikely) gather inside the tank, sink to the bottom because it’s heavier than fuel.
Also, the fuel going into the storage tank isn’t pumped to the bottom, where the contamination potentially sits. It goes in the top, where there’s a lot of viscous damping before any disturbance is made to potential contamination.
Every bowser has a fuel filter and water separator. These catch contaminants greater than 10 microns (one one-hundredth of a millimetre).
If any contamination from any source makes it into a fuel line, cars have fuel filters.
Furthermore I am struggling to see where sediment in the tank would come from. Every time the fuel is transferred from one tank to another along the supply chain, it is filtered. Tanks (at servos) are designed not to break down.
Condensation might be a factor, but water is easy to separate from fuel, because it’s not miscible and it’s so much heavier. (Water is miscible in e10 and would pass harmlessly into the engine…)
Conclusion: This is definitely a non-problem, differentially confirmed by the fact that there’s no epidemic of cars failing in service because they filled up at the wrong time.
Sincerely,
JC
More reports
The all-new Kia Tasman 4X4 dual-cab ute is finally coming to Australia in mid-2025. The covers are off, too. Here’s everything we know so far