Yes, you have one of the earliest types of oil cap with integral dipstick. They are fine and the 0-rings do not deteriorate. However, you do need to keep an eye on the oil tank itself as they have been known to leak oil from the end plate welds and in some extreme circumstances blow the end plate off completely! I reckon this only happens when a fastidious owner tops up the oil tank after the car has been standing for a long while, not realising that a couple of litres of the oil is actually in the engine sump (i.e. wet sumping).
