Not to be a smart azz, but it's rather self explanatory. By having the engine running with oil that is 20 or more degrees cooler, the engine is subjected to less wear and tear, resulting in longer engine life. I have the same engine on my 5 yo Scag Liberty Z 48". But with only 143 hrs run time on it, I'm not overly concerned with installing a cooler. Plus, I change the oil and filter yearly even tho only 30 hrs are racked up each season.