Toyota-Lexus-Subaru-Honda Spark Plug Tube Leaks

Many of the Toyotas have semi-hemispherical shaped combustion chambers that result in the spark plug being placed straight down through the top of the head.

In these instances, the spark plug enters the combustion chamber at the bottom of a spark plug tube that passes through the valve cover and valve area.

If this tube begins to leak, it usually results in very little measurable loss of oil, however, as this small amount of oil floods the spark-plug tubes, it will eventually ruin your ignition wires and cause an engine misfire as they start shorting out.