Overcooled is way more preferable to overheated.
Recent tests done by a famous oil co showed that the engine oil tends to be 30-40 C HOTTER than the water temp, as it does at least as much cooling as the water.
Most oils will start to break down at 135C or thereabouts, so most std cars are on the limit, but that is mass production for you!!
Fit one but with a stat then you have the best of both worlds, the std modine was fitted as it warms the oil quicker, not just for cooling purposes.
tabetha