First of all it costs approx £25 to get a full used oil analysis I do it on my cars so it is available. On the other hand that is the price of a typical 5 ltrs of oil so economically there is no case for doing it.
Offshore where it cost £1500 to change a turbines oil and say tosing production of say £150k it is a good idea to do it in order to extend the oil change to it's longest possible time.
Looking at lots of UOA's I have yet to see any increase in water content for an oil kept in the sump for two years compared to one year.
Unless someone can point me to some other measurement there is no problem with using the oil in the car for two years with low mileage on it.
Mobil in the US done an Aunt Milly paper some 6 or so years ago for the typical Aunt Milly who does a very low mileage in her car and it was their opinion that the oil was still serviceable after 5 years.
Yes the same Mobil who sell oil. The oil will be just fine after two years.
eddie
