[DannoXYZ]

Nah, use modern full-synthetic 10w40 oil and you’ll be fine. Modern oils are way, way better than API SE grade in use at time bike was new.

 

[DannoXYZ]

One thing to be careful about is multi-weight dino vs full-synthetic oils. Dino oils start with low stock 10-weight and add viscosity thickeners to achieve thicker 40-weight hot viscosity. Synthetic oils start from heavy 40-weight stock and add viscosity thinners to get lighter 10-weight cold viscosity.

Distinction comes in when oil is stressed from intense operations & heat which breaks down viscosity modifiers and oil reverts back to native viscosity. Dino oil goes back to its native 10-weight rating. Not what you want at redline and overheating conditions, eapecially on air-cooled bike.

Full-synthetic on other hand, goes back to its native 40-weight viscosity when stressed. No changes in warmed-up conditions and engine-protection remains same.