Understanding Oil Contaminants
By Tom Bock
Based on the increase in oil sample results with low Total Base Number (TBN) and decreased Viscosity the recent heat wave across America has taken a toll on motor oil properties. The excessive ambient temperature is putting a strain on the engines ability to maintain the proper oil temperature in heavy duty diesel engines. Even with 10-11 gallon oil capacities the oil is unable to transfer the heat during normal operation. Oil Coolers are over taxed and when the oil temperature rises above 225 F for an extended period of time the oil will thin out losing viscosity. The thinner oil film will allow metal surfaces to touch together increasing friction and heat. The hotter oil will also “cook” the base additive chemicals and reduce the ability to counter-act any acid that may develop.
Oil that has been overheated will be evident if the TBN drops drastically, viscosity is lower without any increase in Fuel percentage and oxidation level is increasing.
There is not much you can do about the outside temperature but you can take some steps to prevent the oil from overheating and lowering the TBN and Viscosity.
• Top off frequently, do not allow oil level to drop below proper operating level, a full oil pan allows oil to cool faster
•Resist the urge to idle , idling will slow the oil flow and heat transfer
•Check air cleaner for any blockage, restricted air flow will change the fuel to air ratio and increase soot production. Increasing solid particulates in oil will negatively affect heat transfer
•Install and oil temperature gauge, oil should approximately 20 F above coolant temperature. If higher check the oil cooler and Turbo Charger for proper operation.
• Install an oil bypass system that will remove contaminants to allow oil to cool properly, less solids to retain heat means faster heat transfer and cooler oil
•Use a quality oil product designed to function in higher heat environments, semi synthetics and full synthetics are designed to operate in higher heat conditions.
• Using an on board oil refiner that removes liquid contaminants will help to maintain the TBN by eliminating the water (H2O) from reacting with the sulfur in the oil from soot and Nitrous Oxide in blow by gases from forming acids
•Sample oil to ensure oil has proper Viscosity and TBN levels
•Check coolant system to ensure proper operation.
• Review samples to ensure oil does not contain glycol that can enter oil when seals and gaskets are unable to adjust to overheated parts etc. The glycol will affects TBN and Anti-wear additives
Thankfully the summer heat will be ending soon and we can turn our attention to the effects the cold temperatures have on the oil qualities.
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