De-rust and seal the tank

Especially with the motorcycle and the moped, the inside of the tank can begin to rust after a few years. This is especially the case when the tank is made of steel. For older tanks, you should therefore consider rusting and sealing the tank. How this works best, you can read in this article in detail.

Necessity of sealing

Basically, a sealing of the tank is not absolutely necessary. When the tank is de-rusted, however, sealing helps to counteract the rusting. Depending on the de-rusting agent used, a seal may be advisable.

If it is de-rusted with hydrochloric acid, it can attack the steel. De-rusting deposits hydrogen molecules in the steel, making it more susceptible to corrosion. In this case, a subsequent seal should be envisaged.

De-rusting agent for the tank interior

To de-rust the interior of the tank, various means are available:

  • Hydrochloric acid (25%) - is very aggressive but also very effective
  • Oxalic acid is a very gentle de-rusting agent
  • Phosphoric acid also acts as a rust converter

Straight oxalic acid is a proven agent for rust removal of tanks, which is also very popular in the classic car industry. It does not attack paints and paints, nor does it damage the material of the tank inner wall. It can therefore be used in low concentration (about 10% oxalic acid) as an acid bath for rust removal.

The salts of oxalic acid, the so-called clover salt, are even gentler. It contains no more acid and works just as well, but even more gently for the paint and attached parts.

Phosphoric acid is one of the best de-rusting agents ever. It also acts as a rust converter and thus protects against re-rusting. Cola also contains phosphoric acid. But you should not use it in the tank.


Another possibility is to sandblast the tank inside. However, this means a lot of effort and high costs for a specialist. Here is a professional refurbishment often cheaper. As a rule, it costs about 130 - 150 EUR for professionals without additional services.

Tips & Tricks

If there is a risk of rusting, or if the tank has already rusted through in one place, you can have it repaired (welded) by a professional.

Video Board: Restoring a Fuel Tank