Lacquer-resistant fuel-line hose

A layered tubing for use in a motor vehicle, the tubing comprising:

• a thick tubular inner layer formed of a plurality of coextruded and coaxial sublayers of synthetic resins each having a predetermined hardness and a predetermined thickness and designed for use in a temperature range down to -40.degree. C.;
• a thin coextruded tubular outer crack-absorbing layer between 0.1 mm and 0.2 mm thick,
• bonded externally to and surrounding the inner layer,
• formed of a synthetic resin resistant to attack by lacquer solvent over the temperature range of the inner layer, and
• having a hardness equal to at most 0.8 of the hardness of the inner layer and a thickness equal to at most 0.5 of the thickness of the inner layer;
• and
• hardened lacquer directly on the outer layer and itself directly exposed to the atmosphere, whereby if the hardened lacquer on the outer layer cracks under cold conditions, the energy of the crack will be absorbed by the outer layer and not transmitted to the inner layer.

A method of making tubing for use in a motor vehicle, the method comprising the step of:

• coextruding a tube consisting of a thick tubular inner layer formed of a synthetic resin having a predetermined hardness and a predetermined thickness and adapted for use in a predetermined temperature range down to -40.degree. C. and
• a thin tubular outer crack-absorbing layer between 0.1 mm and 0.2 mm thick, bonded externally to and surrounding the inner layer,
• formed of a synthetic resin resistant to attack by lacquer thinner in the temperature range of the inner layer, and
• having a hardness equal to at most 0.8 of the hardness of the inner layer and a thickness equal to at most 0.5 of the thickness of the inner layer, whereby, when hardened automotive lacquer on the outer crack-absorbing layer cracks at extremely low temperatures, the energy of the crack is not transmitted by the outer layer to the inner layer;
• applying lacquer directly to the outer layer and allowing it to harden, whereby if the hardened lacquer on the outer layer cracks under cold conditions, the energy of the crack will be absorbed by the outer layer and not transmitted to the inner layer.