Decking is one of the hardest areas of wood to protect, it is exposed 24 hours a day, 365 days a year and any finish can be expected to last for around a year before requiring a top up, refresher or maintenance coat. Oils are the product that we recommend the most for decking, as it is far easier to maintain and repair over time than a surface sealer such as paint or varnish or coating type decking stain.
Oils penetrate the woods surface and protect from within so will not peel or flake over time. When it comes to maintenance, oiled decking can simply be cleaned and re-oiled once dry, no stripping required.
You could consider Ronseal Ultimate Protection Decking Oil that Ronseal claims lasts twice as long as the standard Ronseal Decking Oil. However the Ultimate Decking Oil is water-based where as the standard Ronseal Decking Oil is solvent-based, making them incompatible with each other. If the original oil is well worn away then you are able to clean the surface with Ronseal Decking Cleaner and Reviver and prepare the deck accordingly for application. It is important to do a test area once the decking has been cleaned and dried to ensure the Ultimate Decking Oil will take okay to the decking and that the desired finish will be achieved.