1991-02-01

Effects of NOx and Unburned Gasoline on Low Temperature Sludge Formation in Engine Oil 910747

It is generally known that NOx reacts with unburned gasoline, olefins in particular, to form sludge precursors. In this study, the authors investigated the process by which NOx and unburned gasoline mix into the engine oil and analyzed the mechanism whereby stop and go driving accelerates sludge formation. It has been found that NOx detected in the engine oil as nitrite ions mixes into the oil in the crankcase. The NOx concentration in the engine oil increases rapidly when the crankcase gas temperature is nearly equal to the dew point of the water vapor in the crankcase. Unburned gasoline is mainly absorbed into the oil through the oil film on the cylinder walls and the oil in the ring grooves. During low-temperature engine operation in stop-go driving (i.e., when the vehicle is stopped), NOx and unburned gasoline are absorbed into the engine oil and, in high-temperature engine operation (i.e., when the vehicle is moving), NOx and unburned gasoline are released from the oil. NOx encounters unburned gasoline in the combustion chamber during the compression stroke and also in the crankcase. It then reacts with olefins in the unburned gasoline to form sludge precursors.

SAE MOBILUS

Subscribers can view annotate, and download all of SAE's content. Learn More »

Access SAE MOBILUS »

Members save up to 18% off list price.
Login to see discount.
Special Offer: Download multiple Technical Papers each year? TechSelect is a cost-effective subscription option to select and download 12-100 full-text Technical Papers per year. Find more information here.
We also recommend:
TECHNICAL PAPER

Sludge and Deposit Control in Automotive Engines - Chemical Leads and Mechanism

920857

View Details

TECHNICAL PAPER

Sludge Formation in Engine Testing and Field Service

881580

View Details

TECHNICAL PAPER

A New Concept in Engine Deposit Control Additives for Unleaded Gasolines

830938

View Details

X