"What a great opportunity I have here to tie the record with three legends," Castroneves told CNBC's " Closing Bell " Friday.
Only A.J. Foyt, Al Unser and Rick Mears have taken the championship four times.
Read More IndyCar in early stages of growth: CEO
In a nod to the past, Castroneves is using the same paint scheme and design that Mears once used.
"I feel like the yellow color brings me a lot of luck," he said. "I feel we are in good shape ... I can't wait to go out there Sunday."
The winner of 98th Indy 500 will pocket about $2.5 million.
Read More Formula 1 racing ... for electric cars?
-By CNBC's Michelle Fox. The Associated Press contributed to this report.