Auto box oil cooler for our 850R

[850R]

The auto box on the R was placed by the previous owner only 4 years ago and less than 25k ago, however we are intending on towing with her at some point soon, with the auto box I've read that an additional oil cooler is recommended, we also are intending to go to the south of France so with variations in gradients and heat id hate to cook the box, one day she will have a proper box an I will do a Manual conversion but if it's not broke why fix it!!

Does anyone have any experience of having this done and any garage recommendations. We are northants based.

Cheers in advance