From my understanding there are 3 places that are common coolant leaks, but for different reasons.
After the 5 year rubber change this seems to happen if the spring clamp on the 17mm coolant hoses are too far back and not up by the flared end in the aluminum tube underneath the hose. Place the clamp just behind the flared end, but not on top of it. This makes a far better tight seal. Keeping the clamp to far back towards the end of the rubber hose can allow some oozing on some engines. After 25 hours of flight time take a few minutes and tighten up any screw clamps. The rubber will settle.
p.s. All clamps on the coolant hoses are better sealing up next to the aluminum flared ends on the metal tubing.
If you live where it gets really cold then you can see a few tablespoons of coolant at times back behind the rear tire on the ground. I learned in class that this happens because of different materials in the coolant pump. The coolant shaft setup is make up of stainless, two ceramic halves and the aluminum housing. Due to different expansion and contraction rates for these materials they can drip at times during cold weather and heating and cooling cycles and drips out the weep holes. It should be no more than a few tablespoons and if it's a large puddle there is another problem.
The last place a leak may show up, but may not always be real visible is up on top of the engine where the 17mm hose 90 degree aluminum tubes are. They can ooze around where they are threaded in. The air flow through the cowl can make this one a little harder to find. The give away is some tiny wet or dried residue barely seen around the base of the aluminum tube where it screws into the flat base. This is very easy to fix. Drain the coolant down past that high point. Take the flange off and heat gun it and the tube will unscrew. You can use either Loctite 243 or better yet Loctite 648 on the threads when you screw it back in. Do not forget to use a black magic marker to mark the tube and flange orientation so it will be in the alignment you want when you re-install it. let it dry over night without coolant to get the best seal. You can see this on YouTube videos.