What type of transmission fluid should be used for a 99 Mazda b-2500 manual pick up truck?

A 1999 Mazda B2500 pickup truck with a manual transmission requires GL-4 or GL-5 gear oil. The specific weight (like 75W-90 or 80W-90) might be specified in your owner's manual. Check your owner's manual for the exact recommendation as it's the most reliable source. If you don't have the manual, contacting a Mazda dealership or a parts store with your VIN is also a good way to get the correct information.