I serviced SHMBO's elderly Renault 5 this afternoon, including a couple of drops of engine oil on the feltpad underneath the rotor arm. Reaching for my trusty oilcan, the thought occured to me that the oil in it was at least 7 years old (straight forward Duckhams as I recall). Clearly it's irrelevant for the particular job I was performing, but I'd like to know whether oil has a shelf life - This stuff looked just the same as it did 7 winters ago. Can anyone enlighten me?
Thanks
Phil
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The oil in question has been around for a few million years before you bought it so I should think it will be OK!
Oil is a refined hydrocarbon and very, very non-biodegradable so will not degrade if stored in a sealed container. The only way the oil can degrade is through oxidisation via contact with air (preferably at elevated temp) or through contact with acids (i.e. those produced in a diesel engine) or through the action of sunlight (unlikely) - oh, and through the shear forces in your engine!
The unused oil should have been no different from the time of purchase.
The only difference *could* be the oils with fancy additives that may become unstable after time - i.e. detergents/surfactants, fixatives, polarisers, etc
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You ask a whimsical, but interseting question here, wondering if anyone will answer; five minutes later you get this. Wow!!
I've just been on a plumbing and heating forum.
People desperate to sort their boiler post a question - two and half months later they get a reply.
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Wow BE, you certainly know how to live!
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Trouble is Darcy, *all* of the machinery "essential" to modern life needs choosing and fixing - but only motors generate any interest.
Bono
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I bought some salt last week, and it has a sell-by date on it. (12/2006)
plain salt. no additives, anti-oxidants or anti-caking agents. just salt.
work this one out ...
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Slay is deliquescent, so the table variaty has additives to keep it free flowing
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Our rountine oil sample test man says yes oil will degrade over time
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Bono,
I may be able to help you on this if you care to mail me.
alvin
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Alvin,
I'm ok for now, but many thanks.
Bono
(*Cave boys, HJ's About)
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A bit further down, somone kindly gave this source of info for everything you want to know about oil:-
www.chris-longhurst.com/carbibles/index.html?menu....l
HJ
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Should a caveat be added for hydraulic oil/brake or clutch fluid which I understand to be hygroscopic and absorbs water quite quickly, therefore the shelf life is probably only 12 to 18 months once opened?
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I have some good quality (Castrol) antifreeze in sealed plastic bottles, about 3 years old. Does anyone know if this is any good still?
Pat
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To say that oil will not degrade is only true in the absence of air,like it may have been all those millennia.But most of it is either additive or some sort of synthetic these days.It will still oxidise,as will the additives.Within reason i doubt if it matters any more,even Castrol R would last 6 months.I still dont like to have any oil around,either in engines or unopened cans,for more than a year.Sealed cans,no probs,how would we store the bargain French Full Synth otherwise?
Interestigly i have just worked out when I last filled my little red pump oilcan,it was 1981.........but I only use it on the lathe,and then not often.
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On a slightly tangential theme: We are constantly told that plastics do not biodegrade and will be around for ever. And yet when my third child was old enough to get on the garden swing the plastic seats had to be changed as the UV had degraded the plastic so much.
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