What type of manual transmission fluid for 1999 Toyota Tacoma?

For a 1999 Toyota Tacoma, it is recommended to use Toyota Genuine Manual Transmission Fluid or an equivalent that meets the API GL-4 specifications. Many owners also opt for 75W-90 or 80W-90 gear oil, but it's essential to avoid using any fluid that meets the API GL-5 standard, as it can be harmful to the synchronizers. Always check the owner's manual for specific recommendations and guidelines.