Disclosed is a method for transporting blended crude oils comprising the steps of; (a) admixing a first crude oil with a second, different crude oil to form a crude oil admixture; (b) determining a first value representing the content of unprecipitated asphaltenes in the admixture; (c) holding the admixture for a period of time at standard conditions; (d) determining a second value representing the content of unprecipitated asphaltenes in the admixture; and (e) either: (i) transporting the admixture if the second value is the same as or within a predetermined range of the first value; or (ii) taking remedial action to prevent asphaltene precipitation prior to transporting if the second value is outside a predetermined range from the first value. Also disclosed is a method for estimating the storage stability of stored crude oils and crude oil admixtures.