Came across this which is sort-of relevant.http://www.machinerylubrication.com/Read/172/lubricant-storage-life
Its titled "Lubricant Storage Life Limits - Industry Needs a Standard
" but if you read it you might reasonably conclude that "industry doesn't need a standard", since they don't appear to have one, nor any basis for one.
Like most "pitches", what it doesn't say is as significant as what it does. There is absolutely no evidence reported here for on-shelf deterioration of motor oils. Instead, its served up as a ready-cooked "given" with a side order of "The sky is falling" Chicken-Little panic salad.
Table 4 (recommended shelf life for indoor storage at 20C) is especially instructive
Major oil company C: 10-30W Motor Oil (mineral) 1 YEAR
Major oil company C: 10-30W Motor Oil (PAO) 1 YEAR:
Major oil company D: 10-30W Motor Oil (mineral) 1 YEAR
Major oil company D: 10-30W Motor Oil (PAO) 1 YEAR:
Independant oil company B: 10-30W Motor Oil (mineral) Virtually unlimited *
Independant oil company B: 10-30W Motor Oil (PAO) : Virtually unlimited
Independant oil company C: 10-30W Motor Oil (mineral) : Infinite
Independant oil company C: 10-30W Motor Oil (PAO) : Infinite
1 year (!) isnít very long, and 1 year to infinity is a pretty wide range.
IF the 1 year has a basis in fact, it could mean that the major oil companies massive (but of course secret) testing of their latest oils, extending over several decades, has told them that their oil is particularly fragile.
OR it could be that their general knowledge of the chemistry of their product makes them think it might be particularly fragile, though its odd that the PAO, plausibly believed to be more stable in an engine, is just as fragile on the shelf.
OR it could be that they wanted to cover their big fat corporate [censored], and pulled the smallest number out of it that they thought they could get away with.
(One might also conclude that either the re-stocking (or re-labelling) costs associated with this short life are carried by the retailer, or the supplier thinks closout specials are good for bizniz.)
Yer pays yer money, and yer takes yer choice