This question keeps getting brought up. so I figured I would post some links with info on it here.
Several manufacturers give a shelf life for their motor oils.
Some have no information available online that I have been able to find. Mobil gives a 5 year shelf life in their FAQ.Pennzoil says a 4 year shelf life in their FAQ. Amsoil gives a 5 year shelf life in this TSB. Chevron (marine products, can't find anything for PCMO or HDEO) is 5 years. Valvoline says no documented expiration date. Go by API rating.
For Shell/Rotella, Redline, Castrol, Royal Purple and Warren (Supertech/Amazon Basics) I can't find any information online.
I did read somewhere that someone had called Castrol and was told 3 years, but nothing to back that up.
I have heard some have called Redline and been told 3 years, 10 years, and no expiratiion. Again, no proof, just remember reading it here at some point in time.
I did not see anything that differentiated conventional oil and synthetic oil shelf life.
The ironic thing is that finding the date of manufacture of the oil can be daunting at times depending on the manufacturer.
Pennzoil is the easiest, the date is a simple date (day, month, year).
Castrol is fairly simple also, letter is plant code, then five numbers. First two are the year, last 3 are the day of the year.
Mobil uses a code, the first three numbers are the plant, the next two number are a 2 digit year, then the month letter (A=Jan, B=Feb, etc, with letter "I" being skipped) then 2 digit date. Mobil also has an older date code format (2009 and earlier) that is similar.
Valvoline uses a similar code to Mobil, but is month letter, day and year.
Shell/Rotella has a long code, first comes the plant (usually letters), then a batch code, then the date (will be numbers, month,day,year, no spaces) then time made.
Amsoil only has a batch code, not a date code, so you have to contact them to decipher the date from the batch code.
This is not a complete list, and not everything is covered here, but I think this gives some basic information.
Also this refers only to oil in original, unopened, sealed containers stored in "optimum" conditions (i.e. indoors, relatively stable environment, not just sitting outside or the trunk of a vehicle. Detached sheds could be OK depending on ambient temps and humidity).
The argument that the oil is millions of years old and won't expire is not valid. Would you pour crude oil into your engine? Did not think so.
Engine oil is a refined product, and synthetic oils are highly refined, and contain other additives.
Some of these additives may fall out of suspension, hence the recommendation to shake the bottles before adding.
I know Blackstone Labs did a test back in 2012 on new oils from the 70's and 80's and it was fine to use in vehicles from that era. The article no longer exists though that I can find.
I don't want this to become my personal opinion post, and won't tell you to or not to use an older oil. Only you can decide that.
But I will post a few of my opinions here, and these are just that, my
- If the API/ILSAC/ACEA spec and viscosity of the oil meets or exceeds the engine requirements, no issues will arise using that oil regardless of age (again, sealed container, stored appropriately, etc).
- Most of these are not truly the expiration of the oil, but more an expiration on the API rating. (guess what the average API life is since 1967... (hint: 5.7 years)
- I also think it is a legal way out of any issues with using an older oil that may not have been stored under ideal conditions.
- Valvoline must make some special oil, since they are the only one that says oil does not go bad.