Spark ignition gasoline and compression ignition diesel engines differ in how they supply and ignite the fuel. In a spark ignition engine, the fuel is mixed with air and then inducted into the cylinder during the intake process. After the piston compresses the fuel-air mixture, the spark ignites it, causing combustion.
1 If your skin is too sensitive, dilute tea tree oil with some baby shampoo. Add 10-20 drops of tea tree oil to 1/2 cup of baby shampoo. Use this daily to wash your scalp and hair till you get rid of itchy scalp.  You can even massage diluted tea tree oil to your scalp.
Â©iStockphoto.com/dawn liljenquist. An itchy scalp is a common ailment, one that may be the result of a skin condition or not. Beyond the discomfort of the itchiness, an itchy scalp can cause several problems. For some people, the condition can be embarrassing. It might be socially unacceptable scratch one's head in public, and the fear of unattractive flakes in the hair or on the shoulders can make some uncomfortable and self-conscious.