I got a garret airresearch m10 turbo getting ready to put a junkyard setup on my car and i know it's oil cooled and i think it's water cooled cuz thers 2 extra holes beside the oil feed and return holes. my question do you have to use water lines on a oil and water cooled turbo?

 

from what i understand.. no.. you don't HAVE to use it.. but its not that hard to use it so why not?? you have to change your oil more often if you don' t use the water cooling.. and i can imagine your intake charge temp is probably a little higher...