Will my oscars attack my turtle?

I'm about to buy a 100 gallon tank I know I need more space like a 120 gallon but I'm only 14 and I have 269$ bucks mean while I have two tiger oscars in a 20 gallon that's why I'm upgrading but I want to put my 5inch RES turtle in there will they attack him I have put a little Oscar there before and they killed him