Im looking at a used GTV with a V6 TB and the seller said that the oil cooler needs replacement, and wouldnt reccomend doing long drives before that. My question is, what other problems might arise from oil cooler failure? Im guessing that if everything goes really well, all I have to do is fit a new cooler, change the oil and done, but what would the "black" scenario look like?
Oil cooler (or the unions) fails at speed, sump gets pumped dry, engine runs for a short period of time without sufficient lubrication (by the time the low-oil pressure lamp is on it's too late!), engine is trashed and needs a rebuild.
The real risk of damage is if the unions fail suddenly whilst you're driving, and the oil pump pumps the sump out dry... If it's just weeping at the moment then it needs doing, but so long as the engine hasn't been allowed to run with low oil the it's probably fine.
The existing cooler could just have corroded pipes which could let go any minute. Maybe even a slight leak. It doesn't mean the engine is trashed (it can't be, if the cooler is just "weeping" ... as long as it hasn't been doing it for years and the oil level has not been topped up.
My money is the pipes look flakey with rust and the guy is just nervous they'll start leaking anytime soon.