Injection of low salinity water in some crude-rock systems may provide substantial improved oil recovery. However, the mechanisms are not fully understood. There is not much understanding of what type of crudes or what type of rocks lead to improved oil recovery from low salinity water injection. In this work, we measure acid and base functionality of the crude oil as well as brine-crude oil interface viscoelasticity and contact angles to shed light on low salinity water injection in sandstone rocks. We use three different crude oils from three different reservoirs from the Middle East. Two of the oils are heated to 55 °C to remove some of the light components to broaden the range of oil variables. We carry high salinity and low salinity water injection in Berea sandstone cores saturated with the whole crudes and the heated crudes. In some tests after high salinity water injection, we perform low salinity water injection. All rock/brine/crude systems examined show water wetting conditions. In one of the three whole crudes, we observe a significant improved recovery from 53% to 66% with low salinity water injection. In another whole crude, there is no increase in recovery with low salinity water injection. In the third whole crude, there is limited improved recovery with low salinity water injection. In the heated crude oils (with removal of light components) the recovery is improved significantly by low salinity water injection. Various measurements show that total acid number and total base number as well as the interface viscoelasticity contribute to improved oil recovery from low salinity water injection in a water-wetting state. Our data also show very little improved oil recovery when low salinity brine is injected after injection of high salinity brine. In our measurements, the pH of the produced water in the sandstone is about 10. It does not depend on the salinity of the injected brine.