What type of gear oil for 1978 evinrude 25hp outboard?

For a 1978 Evinrude 25hp outboard, you should use a high-quality gear oil specifically designed for marine applications. The recommended type is typically a 90-weight gear oil, such as Evinrude/Johnson Gearcase Lubricant or an equivalent marine-grade oil. Always check the owner's manual for specific product recommendations and specifications to ensure optimal performance and protection.