I have a Kohler Courage 25HP engine in my riding mower and don't have a lot good to say about it. The most recent issue is that I burned through 5 quarts of 10W30 over the course of mowing my yard. I decided to check as it had started smoking and blowing a fog of oil all over and it was a quart down after about each 15 minutes. I talked to a small engine guy about possibly rebuilding this and he said it wouldn't be worth it based on the cost of the internal parts I would probably need. He told me to just run it and keep the oil topped off and changed until it gives it up. He says that the Courage is the "economy" or "consumer" grade engine and pretty much a disposable. The Command line is what you want. This engine seems very picky about oil. I ran a Rotella T6 5W40 in it and it didn't burn much. The 10W30 that burned like mad was some Valvoline Nextgen recycled oil. I had to top it off with some Castrol Edge 10W30 I had just to finish the lawn. I didn't have a full fill of this oil but noticed consumption went down dramatically. I had used some O'Reilly full synthetic 10W30 in the past and it liked to burn that also. I am just wanting to prolong the life of this engine as long as possible and not blow fogs of oil out the exhaust while mowing. I found a Mobil 1 synthetic 15W50 and was wondering if this might be a good option. I want something that won't just squeeze past the rings anytime I hit resistance. That Valvoline Nextgen blew oil fogs anytime I hit tall grass. Obviously there is something up with the engine but certain oils seem to cause more issues than others, even in the same viscosity.