If your asking the question... You will most definatly require the workshop manual, with out this publication you cannot hope to change the oil cooler from an MS4 series gearbox.
WSM retail around the £25 mark from your local VP dealer. Considering that if you make a donation to an R.N.L.I charity box then I will email you a copy, its a 4,203 KB Adobe Acrobat Document.
I will need an email address, suggest you PM that rather than display it here, but up to you.