on a water fed and oil fed garrett t25 which is more likely to be the feed for the oil and the feed for the water.
one pipe is noticeably bigger than the other and is connected using a banjo bolt. the other is thinner and connected using a different fixing (not banjo thou)
any help figuring this out would be great

 

look inside the holes, one will be black the other like rusted or something..

usually the water holes are threaded in the cast housing while the oil ones are flanges.

 

The easiest way to tell is that the water jacket's inlet / outlet are the same, whereas the oil inlet / outlet are different (inlet is round, outlet is usually square). Also, if you look in the oil outlet, you'll be able to see the turbo's guts (shaft etc).

 

theres no rule of thumb then like oil feed is always attached with banjo bolt or something?
thanks

 

the exhaust housing flange points up. with that pointing up, look straight down at the top. that inlet in is the oil feed. now flip the turbo upside down so that the exh. housing flange is pointing at the ground. you are now looking at the oil return. now you can figure out by process of elimination the coolant. also, the coolant inlet/outlets are threaded goign into the turbo (so you can cap them off if you dont feel like using them)