We put Til , mustard oil and black cloth on ' LORD SHANI ' in order to get relieve from pains and troubles in our lives. These are the ways to appease Lord Shani. This putting of Til , mustard oil and black cloth on ' LORD SHANI ' is the way of worship. After Lord Shani became free, he requested Lord Hanuman to give him some oil to reduce his miserable pain. Lord Hanuman offered Lord Shani some mustard oil. After massage of that oil on his body, the pain was removed instantly. So that's why it is a tradition to offer mustard oil to Lord Shani Dev.
