Porsche 911 "#Ölklappe". To make the oil cooling system of the #911 even more efficient, #Porsche moved the oil filler neck to the outside in the 1972 model year. However, this resulted in many owners and gas station attendants refueling the 911, mistakenly, at the oil flap. This led to many #engine failures. Therefore, the oil filler neck disappeared again the following year. Today, the "Ölklappe" 911 are a popular collector's item. Take a closer look: www.classic-trader.com/pn316648