I change the rod out when the tolerance is out more than .0025". If taken care of, that is right around the 5 gallon mark give or take. I have run the R7 rods in a couple engines until the engine ran erratic because of too much play and the timing and compression were changing as the engine ran with all that slop and I got around 9-10 gallons out of it but definitely not recommended. The instructions say to change out the rod every 4-6 litres or 1-1.5 gallons but that is a little too safe. You should be able to squeeze 3-4 gallons out of a rod easily if treated well. That means preheating the engine before each start, keeping an eye on bearing and rod wear from time to time, running good fuel with a good oil package and keeping a good tune on it while keeping foreign debris out. It can be hard to do all of the above all the time but it is possible.