Do cylinder heaters cause the oil to drain off the cylinders?
Occasionally we get this question from someone who fears that heating the cylinders is bad because it may allow the oil in the cylinders to run off, so the cylinders may be “dry” when the engine is started. This is not a concern, because: • Our cylinder heaters raise the cylinder temperature about 70-90o above ambient, like a warm summer day. So oil runoff is no more of a concern when preheating than it is when your aircraft is sitting on a hot ramp in summer. • The cylinders are lubricated by splash oil. With warm preheated oil there is good splash lubrication immediately on engine startup. • The risk of engine damage from not adequately preheating is well documented, and concern about that should far outweigh any concern about “oil runoff”. If runoff still concerns you despite the above, you can minimize it by using a synthetic oil like Aeroshell 15W50. Synthetics cling to metal surfaces, so you have an oil film on startup.
