The oil cooler is simply an improvement for engine longevity. TW's have been ridden successfully without oil coolers for [s]35[/s] 25 years now (thanks PSC). But, in hotter climates oil temperatures do get hot enough to cause a breakdown in the oil. Most have alleviated the problem by changing the oil often, like every 500 miles. Since the TW only holds a quart, it's not a big deal to do so. Here where I live it will be 111 degrees later this week. I put on an oil cooler for my TW's benefit, and for my own peace of mind. It does help that a forum member offers a trick oil cooler adapter at a reasonable price. Lizrdbrth comments on the oil temperature thing on pages 7 and 8 in the oil cooler thread here. I haven't heard of any heat related problems with the engine operation other than pinging when it gets too hot.