After some advice. Now driving a 57 reg Scania R420 6x2 unit with twin tanks. I think they are 300lt each. Brimmed them on Saturday ready for today. Went from Thurrock to Plymouth fully loaded and I am now parked up at Basingstoke on my way back to Tilbury with the fuel gauge in the red! Is this about right? 600lt seems a bit much for that run. No fuel card either as they haven’t come in yet! Or is the reserve large on the Scanias? Never had one before!
Last time i had a 6 x 2 Scanny the two ridiculously small tanks combined only made about 350 litres.
Now you’ve gone down to the red you should know exactly what the useable capacity is…remember to shine a torch in before filling so you’d know for future reference how low into the red you dare push it?
Have a look in both tanks, dip them with something if you can.
There might be a tap underneath and one tank could be switched off. 
Sure they are bigger than that. It’s. Ex Stobarts if that helps! Will get my torch out and have a look!
tap the tanks you’ll soon know if ones still full its go dong instead of boooong… 
A 300 litre tank is bloody big, about 3ft long and 2ft square, type you see on CF Dafs etc, i bet your tanks are the standard 2x2ish ft square and about 18’’ long.
dont seem right that i could go from manchester to glasgow and back with a load of timber before id top up and even then i was not in the red like someone else said are you sure its using both tanks and one is not shut off
could also be a dodgy fuel gauge i have had a few that never read right
You should have used 280 - 320 litres on that run.
No more.
430miles at 7miles per gallon = 62 gallons ish x4.54 = 280litres ish
Simples.
Well that’s what I thought! Even my Premium I used to have did better than this! Another question for the Scania experts, why is there no audible warning for the indicators? Or is it turned off?
Mine is stamped 300 cu decimetre which I’m assured is 300 litres, but even when at the bottom of the red on the fuel gauge ,the most I’ve ever got in is 230 litres.
Sounds like the same tanks as this, so maybe inaccurate fuel gauge. Sure it can’t have used that much fuel in a day!
my Volvo holds 700lts in 2 tanks, and I can do at least 2000kms before I even think about looking for fuel
but I am averaging about 10mpg
tonyb70:
my Volvo holds 700lts in 2 tanks, and I can do at least 2000kms before I even think about looking for fuel
but I am averaging about 10mpg
That must be a big reserve as 700l= 154 gallons. And 2000k = 1250 miles
1250 divided by 154 = 8.11 MPG.
It could be that one of the tanks are split it could have been used on walking floors so you haven’t in as much as you think you have ex stobarts have quite a few on walking floors
rgt1973:
After some advice. Now driving a 57 reg Scania R420 6x2 unit with twin tanks. I think they are 300lt each. Brimmed them on Saturday ready for today. Went from Thurrock to Plymouth fully loaded and I am now parked up at Basingstoke on my way back to Tilbury with the fuel gauge in the red! Is this about right? 600lt seems a bit much for that run. No fuel card either as they haven’t come in yet! Or is the reserve large on the Scanias? Never had one before!
You’ve got less than 500 lt onboard if they’re standard Scania tanks,I’ve never put more than 450 in any Scania I’ve used. Check that the breather pipe on the 2nd tank isnt blocked, thats the tank without the stack in it, if the breater pipe is blocked then it’ll struggle to draw through from that tank to the primary. If you take the cap off to manualy checke the level as others have suggested they’ll be a bit of a vacum as you remove it, though release off vacum will help some draw through.
Just a thought 
You think they are 300 ltr tanks. A 45 gallon drum, We all know how big they are, is 205 ltrs.
Mine has 2 300litre tanks and the most I’ve ever got in 1 tank is 250litres running it as far down the red as I dare.
rgt1973:
Sure they are bigger than that. It’s. Ex Stobarts if that helps! Will get my torch out and have a look!
I can tell you now matey one of those fuel tanks on the R440 6x2 is not 300lt. I’d say they were about 150lt. The Scania G400 (one fuel tank) is 300lt and that’s way bigger than a single one of those. I think it’s like that as the midlift takes up space where the 300lt tank would be on the 4x2 unit.
Check that tank 2 is actually empty, it may be turned off or have a blockage / airlock
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Modern 4x2 Scania tractor units can hold up to 1,500 litres of fuel.
6x2 Scania tractor units can hold up to 1,000 litres of fuel, depending
on the axle configuration and emission technology.
Other typical 6x2 capacities can be 540, 810 litres and others.
Dipping the tank is impossible on most Scania tanks - they usually have an
anti-theft, perforated cone that prevents you dipping or actually seeing the
fuel level.
The sound from tapping the tank is never easy either.
You must fill Scanias in the correct sequence.
There are stickers on new tanks telling you which tank to fill first.
It is NOT always the offside tank first.
You could have an air lock. You could have a fused fuel guage.
You could have a blocked fuel line. You could have run out of fuel.
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I think the tap on the N/S tank is turned off.