Easy-open quality seal. STP 4-Cylinder Oil Treatment is formulated to provide high stress lubrication for four cylinder cars and light trucks. Today's smaller four cylinder engines work harder and run hotter than six and eight cylinder engines. This can cause motor oil breakdown, the weakening of oil's vital protective properties. STP 4-Cylinder Oil Treatment: fights motor oil breakdown, adds viscosity to counteract thinning, increases anti-wear protection, adds anti-oxidant to resist oil deterioration, contains dispersants to help maintain engine cleanliness. STP 4-Cylinder Oil Treatment's exclusive formula provides an extra margin of protection for the most rigorous 4-cylinder engine operating conditions.