Total Base Number (TBN)

Description

Determines the reserve of alkaline additives in motor oil, necessary to neutralize aggressive acids formed during fuel combustion.

When gasoline or diesel fuel burns, aggressive sulfuric and nitric acids are formed, which, along with blow-by gases, break into the lubrication system, aiming to destroy the engine. The Total Base Number (TBN) is the alkaline armor of your motor oil. The RENA laboratory measures this indicator so you know exactly whether your oil is capable of continuing to neutralize acids or if its service life is completely exhausted. This analysis is the only scientifically sound way to establish the correct (safe) oil drain interval for your equipment fleet, considering the quality of the fuel you use. Accurate measurement (ASTM D2896) is performed by potentiometric titration with perchloric acid on an automated Metrohm complex. A motor oil sample is dissolved in an aggressive mixture of chlorobenzene and glacial acetic acid. Special electrodes are immersed in the solution, and the instrument begins to dose a strong acidic reagent (perchloric acid). This acid reacts with the alkaline detergent-dispersant additives (calcium/magnesium sulfonates and salicylates) contained in the oil. The microprocessor measures the change in the electrical potential of the solution as the titrant is added. When the entire reserve of alkali in the oil is completely neutralized, the instrument records a potential jump and calculates the base number with high precision, which is traditionally expressed in milligrams of potassium hydroxide per gram of oil (mg KOH/g), although an acid was actually used for neutralization.