freeman

As most you know NAPA has periodic sales on Mobil1 0W40 and 5W50 as well as their other oils.. The sales are regional, not nationwide. Two months ago I bought a case of 5W50 for $5.35 a quart on sale. It usually costs over $9.00 per quart. This week, NAPA announced a sale in our area of Mobil1 for $4.99 a quart. I have just had my annual oil change performed in June and will not need to replace my oil until June of 2020 given that I drive my 991 less than 7000 miles per year.

My question is, how long will 5W50 remain stable in unopened bottles? Can I expect stability for at least a year? What is the maximum period I can expect oil to remain stable in unopened bottles? Should I buy oil that probably not be used for 2 years?

ericmeds

Being that the EU oil change interval for 991's is 2 years when it's already being actively used in the engine, you would for sure be fine for a year or more. I bought some 0-40 on a sale as well a few months back for my oil change this September.

VII7

Recommended is 5 years.

LexVan

https://rennlist.com/forums/general-...tion-date.html

Sidvicious7

As stated above:

https://mobiloil.com/en/faq/ask-our-...mobil-1-quarts

DBH

Straight from the horses mouth: "ExxonMobil recommends a five-year maximum shelf life for engine oils, including Mobil 1™ synthetic motor oil."

Charles Navarro

Oil stored for longer than the recommended shelf life can have additives fall out of suspension. Simply shaking the bottle vigorously before dumping it out is all that is needed.

If the bottle has been opened, that's a different story. Shelf life will be significantly less after opening.