Going 5 years might be a stretch as there are many variables involved in oil formulations and how they are packaged as well as the environmental effects. For example, hermatically sealed cans are more effective in preventing any moisture contamination that the plastic containers used by many companies.
In the military, they obviously have a shelf life problem with the way they buy, store and distributed their packaged petroleum products. What they do is to have an established re-test frequency for each class of product that requires samples to be taken at specific intervals and subjected to a series of laboratory tests to see whether any changes have occurred such as separation, loss of anti-foaming, precipitation of ingredients, haziness, etc. For engine oils, the re-test frequency is two years much like what Motul does. For gear oils, the frequency is only 1 year as those formulations have a tendency for the anti-foaming additive to coalesce which makes it less efective.