1

I always keep a quart or two of oil in my trunk for "just in case" purposes. Currently, I have one sealed quart and one unsealed, half-used quart. Both Castrol 0w30 full synthetic.

I bought them both last year, they were in my trunk all (Canadian -30C) winter. Are they still okay to use for my next oil change?

Same question for a sealed (still in shrinkwrap) oil filter.

  • As long as you will live. Google says 5 years but I think that is BS. – Moab Apr 18 '18 at 19:57
  • I'm really not sure about the oil, but the filter, as long as it stays dry and wrapped, will last indefinitely. – Pᴀᴜʟsᴛᴇʀ2 Apr 18 '18 at 21:31
2

Unlike brake fluid, oil isn't hygroscopic (absorbs humidity) and is not capable of chemical dissolution with water, which produces new substances.

An added note: DOT 3 and DOT 4 are glycol based, which is hygroscopic; DOT 5 is silicone based, which is not hygroscopic. Hence why you should never mix the two, as it will become a kind of gel substance.

Sure, oil and water are capable of physical dissolution which is purely mechanical; an example would be shaking a bottle of Italian salad dressing. The different ingredients mix, but don't form a new substance.

You would be talking adding lot more water in the mix to even have any adverse affects (blown head gasket and such), than just a little bit of humidity which would most likely evaporate at running temperature anyway. And it would take a whole lot of water to have compression issues like hydrostatic lock and ruin your engine.

If it were me, I'd happily use what you've got for my next oil change.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.