phiggsbroadband is correct. There have been major advances in both oil technology and engine materials used in construction in the last 30 years. However, it's the auto industry that is leading the developments.
Aircraft engine designs are very slow to change, and new aircraft engine construction materials slow to be introduced, due to the need for extensive proving and certification.
The newer improved oils have probably had some impact on lengthening piston aircraft engine life, but it's a moot point when you have overhauls set on fixed hour limits.
Multigrade oils are base lubricating oils with "viscosity improvers" added. These VI's are long chain polymers that have the curious (advantageous) molecular properties of molecules lengthening as they cool and shrinking as they heat up (conversely to what you'd expect).
As a result, they thicken the oil viscosity when hot, and thin it when cold. This allows the base lubricating oil to perform better over a much wider temperature range.
Oil industry chemists then add additional chemicals to the oil that improve lubricity, that soak up and neutralise contaminants, that prevent corrosion and foaming.
The search is on constantly, for newer chemical additives to oil that increase the lubricating oils ability to deal with increased bearing pressures, to cope with higher levels of oil shear, and higher levels of contaminants, and to reduce oil burn.
This is the area where the greatest developments have been in oil in the last 30 years - in the improved polymers and additives that are available today, as compared to the 1960's and '70's.