Simplify the following text for a Grade 4 native English-speaking person.
Original: After joining the NHL , the Oilers went on to win the Stanley Cup on five occasions : 1984 , 1985 , 1987 , 1988 and 1990 .
Simplified: The Oilers have won the Stanley Cup five times , in 1984 , 1985 , 1987 , 1988 , and 1990 .