It's a SPAD, not a kit or an ARF. Just follow the instructions that came with the engine for break in. The 5% will work just fine but it tends to make it a tougher job to get the low end adjusted correctly. I'm like Chuck, I would run 15% but I have used 5% and 10%, it's just easier for me to get the 15% so I run it in all my glow engines. It's more about the oil content then the nitro when breaking in an engine, 18 to 20%. I run Power Master and the oil is blended with a little castor in the content.