The specific manual transmission oil for a 2002 Volkswagen Jetta 2L 5-speed is:
* Viscosity: 75W-90
* API Service Classification: GL-4
GL-4 vs GL-5
GL-4 and GL-5 are two different types of gear oils that are used in manual transmissions. GL-4 is the older specification, and it is designed for use in transmissions that have moderate loads. GL-5 is the newer specification, and it is designed for use in transmissions that have heavy loads.
The main difference between GL-4 and GL-5 gear oils is the amount of sulfur they contain. GL-5 gear oils contain more sulfur than GL-4 gear oils, and this can cause problems in some transmissions. The sulfur in GL-5 gear oils can react with the copper components in the transmission and cause them to corrode.
For this reason, it is important to use the correct type of gear oil in your manual transmission. If you are not sure what type of gear oil to use, you should consult your vehicle's owner's manual.
