Dirt and surface contamination can affect the finish. Agree suitable ordinary cleaning as part of the preparation rather than assuming oil covers it. Structural deterioration, hazardous materials and repairs to unsound boards remain separate from a maintenance oiling task.
Share the exact proposed oil, timber information and previous treatment before purchase. Similar product names can describe different systems. The quote should identify the selected compatible treatment; substituting a different can on the day can change the preparation and application requirements.
Provide the old product label if available. A penetrating oil maintenance treatment is different from applying a film-forming deck paint. An existing incompatible coating may need separate preparation, so a new oil should not be selected from colour preference alone.
Apply the compatible oil according to its coverage and application instructions to the agreed prepared accessible deck surface. Scope limits: Compatible penetrating-finish maintenance on sound timber only. No structural repairs, hazardous stripping, waterproofing systems or guaranteed restoration of damaged boards.