Toyota Repair: Oil leak, toyota camry, ring seal

Question
I have a 94 toyota camry 2.2 liter 4 cylinder and I have an oil leak . I found out that it coming from the oil cooler but I'm not sure how to remove the oil cooler. it looks like I might need a 23 or 24mm hex tip for my rachet. I plan to replace the o-ring please help.

Answer
There is an o-ring seal under the oil cooler housing, I don't remember but you can use either an allen socket or a deep socket that fits over the threads, the repair manual doesn't specify the size it just says remove it, the allen socket is either 12 or 14mm, the nut is either 24 or 27mm.
Use a ruler that measures millimeters to check.