This paper outlines some of the significant changes in turbine oil oxidative stability requirements over the past five to ten years, and illustrates how these have been met using mineral oil-based products with differing antioxidant systems. It also considers possible future requirements and how these may be met. Use of a modified Federal Test Method 5308, and ASTM tests D 2272, D 4310, and D 943 in formulating new turbine oils and evaluating their oxidative stability is also described and contrasted. An example of oil condition monitoring on a used turbine oil from the field to assess its oxidative degradation is also given.