V6 is not scary. Regular oil changes and belts on schedule will keep it happy. It is a good idea to stick diagnostics on it, but anything serious will be pretty apparent in the warning lights or by driving it. I'd check the oil cooler (OSF) for leaks, and check all other potential oil exit points. You are unlikely to detect any of the exotic potential failures. As to driving it, you, should be able to floor in in 6th at 1500 and smoothly go to whatever speed you desire. Fluffing or hesitation is not good.
In traffic, the temperature should be steady. Regardless of speed or lack of speed, the temperature should be rock solid at 90c. If it climbs, suspect radiator.
Check that the clutch is light and engages properly. A pain to fix. Boot it in 4th, any slip and budget for a change.
On a GT check that the windows work properly - a bigger problem than the engine IMO.