Howdy and welcome to the forum
Crusing 4 hours from ATX to Galveston at about 80 mph mid-day at about 95 degrees my oil temp plants itself right about 240. I can easily hit temps of 240-250 with some very spirited driving in 2nd and 3rd gear. But I keep a keen eye on the temp and never push it for very long.
The long and short is, if you track this car you should get an oil cooler. If you drive the car on the street like you're on a track, you should get an oil cooler and gtfo the street and onto the track. If you drive the street with only occasional spirited driving and don't see the oil temps pushed past 250 for prolonged periods then you don't need an oil cooler.