I would like to install a 40-50 gallon in-bed aux tank. I like the idea of not having to make many fuel stops with the 5er attached. I haven't decided on a gravity feed or pump feed, but I'll save that one for later. My concern is when I'm not towing. When not towing, should I keep both tanks full? My truck is not a daily driver, so it will be the next camping season before I use much fuel. Or do I leave the aux tank empty and just used the regular tank? I always keep the boat fuel tank full over the winter to prevent water in the fuel from condensation. Are there additives for storing diesel like Sta-Bil does for gas?

Thanks in advance

 

 

If you absolutely will not use a full tank of fuel over the winter, I would leave it full with an inline ball valve closed.

1. A full tank doesn't allow for much moisture.
2. You're always ready in case of a natural disaster.

Biggest negative is you're hauling around extra weight buts its not that big of a deal.

 

 

I've been running a 60 gallon aux tank since '98. I fill it when needed and usually keep it empty when I do not need it. I've personally never had a problem with water in fuel. But, that does not mean it never happens. I'd be more worried about leaving just a little in there for a long time (6 months - year plus); empty I have zero worries. I can say the same thing about the 110 gallon transfer tank I have on the back of my F550. I have ran valve, inline filter and pump the entire 20 years on the aux tank. I really do no like the straight gravity system but many people do it with no problems.

I have recently upgraded to a new tank and pump/filter setup but that was more a want to than anything else. In this one used a water separator (filters as well) but once again, I feel it may be overkill but others have reported filling up with water instead of diesel (maybe a slight exaggeration).

 

I am looking at the Titan Sidekick 15 gallon tank myself, they attach to the bedside and take up wasted space in the wheel wells.