Owatrol rustol-owatrol Rust/Paint Additive 1 Owatrol Oil, for treating rusted surfaces Apply Owatrol Oil wet on wet, as fast as rust will absorb it until an even sheen is achieved. For lightly rusted surfaces use a mixture of 1 part Owatrol Oil to 2 parts Metal Primer. Increases actual paint coverage by up to 25% or more. Coverage: approx. 18m?/ 1L.