Well, I have the old Greneral Grievous from 2005, and it is almost 10 years old. So, by the time, it's torso became like yellow-painted. Tell me what can I do to clean it. Please?
In general, legos can be un-yellowed by soaking in a combination of hydrogen peroxide, oxyclean powder (or sodium percarbonate), under sunlight or UV light. Or use Retr0Bright. Certain colors of painted decorations (such as gold) will not hold up well to the cleaning, but plain pieces and some colors do hold up well.