Leakdown readings will show less leakage if performed when the engine is still warm from running. On the other hand, leakdown testing should be regarded as a tool to locate problems that are present from one cylinder to another. Results can vary depending on the level of pressure applied to the cylinder, the efficiency of the tester, and the expertise of the testor. Don't focus on trying to attain an elusive 1% reading but rather look for gross leakage such as 15% or more in one cylinder or significant variations from one cylinder to another. For general purposes, variations of 5% might be a sign of a problem on one cylinder. If problems seem to be present there are several strategies that can be used to narrow the range of possible sources. First, I'd run a check and determine if significant variation is present.
