Here's why:
* Separate systems: The engine and transmission are two distinct systems with their own lubrication requirements.
* Different oil types: Engine oil needs to be able to withstand high temperatures and protect against wear and tear. Transmission oil is formulated to handle the specific demands of gear lubrication.
Always check your owner's manual for the specific oil types and capacities for your 1981 GL1100 Honda Goldwing.
It's important to use the recommended oils to ensure optimal performance and longevity of your motorcycle.