This is a 1961 - 1964 Rambler designed diecast aluminum block. It has been given a bad reputation over the years as being unreliable. Mostly due to the lack of regular scheduled maintenance, rather than a design flaw. Our 1963 Classic Cross Country Wagon currently has 91,000 miles on the aluminum engine without a head gasket failure.
We have found that the engines run extremely well on synthetic oil. As this oil is rather expensive, ensure you are not burning oil before you switch. The synthetic oil also flows a lot easier, so ensure that your seals are in top shape.