gsd ... add your car details and location to your profile .. saves being asked a trillion times !!
There are several members here who have done oil coolers themselves in less than a day !! ( Not me though
)
Ask and you'll get all the help and advice you need 
Its a 3-4 hour job plus flushing......
Is that you Omega Gods or us mere mortals ??
I'd probably allow 8 hours knowing my luck/skills .. and I probably am missing at least one important tool ... "crowsfoot spanner" I believe ?? though why you have to mutilate a bird I've yet to work out .... 
Thats how long at the second attempt......
19mm crows foot spanner is the weapon of choice!
Pasrt required.
Oil Cooler, plate, nuts and Orings (all part of kit at 90 quid)
4 coolant bridge douty wshers (about 3 quid)
4 cooler pipe to cooler metal washers (about 2 quid)
Oil
Oil filter
Some suitable detergent to flush the coolant system
Anti freeze,
So call it 4 hours plus the bits.....500 quid tops at a dealer.