For a low use vehicle, it was historically recommended to keep the gas tank full. The reasons were twofold:
- Prevent rust from forming in the metal gas tank
- Prevent water from forming in the gas tank due to evaporation and condensation
Nowadays, I wonder if either of those two rationales apply.
Are there any mainstream production vehicles that still use metal gas tanks? If not #1 is moot.
Given the advanced seals on current gas systems, is #2 still a factor? If so, why?
Overall, for a low use vehicle, I wonder if it is now advisable to keep the gas tank at 1/4 a tank or less. When I say "low use", I'm thinking of a vehicle that is driven 2-4 times per month for a total of about 100 miles per month. That way, when it is driven, and a little fuel is added, more of the older gasoline is replaced.
If a vehicle is driven 2-4 times per month for a total of about 100 miles per month, I don't think fuel additives are necessary.
For a low use vehicle (as defined above), in order to keep it healthy, how much gasoline should be kept in the tank?