When changing oil from five-litre cans, I usually keep the remaining oil in the original containers until I am able to combine all the left-overs for a complete engine fill. Obviously, some of this oil will be older than the rest by as much as six years. I decided to contact the customer care service offered by one of the oil companies and was advised that oil had a shelf life of two to three years. This means the oil I had kept could not be pooled and had to be discarded. This information surprised me, and I suggest that other motorists like me be informed via your magazine that this practice is taboo. It also makes it necessary to check the manufacturing date of oil supplied on the forecourts of filling stations just in case the oil is outdated. Does CAR agree with this advice?
KEN HOLTON -By e-mail
Some overseas oil companies claim a shelf life of 10 years for sealed cans. This makes us think that the oil company you referred to was being too cautious, or else the helpline was manned by an untrained person. Unfortunately, this seems to happen very often, not just in the case of oil companies. Obviously, an open can will allow in dirt, but if the remainder after each engine fill is collected in a clean container then we cannot see why the oil should deteriorate so much faster. What you do with the oil gathered in this way depends on the type of car you have. We don’t see any reason why you cannot add the oil to the sump of an old banger, but we would not use it on a fairly new car.
