, vice president of research with D-A Lubricant Company
, explained that EGR is not new technology , but that diesel engine manufacturers are using it at higher levels than ever before.EGR has been used in gasoline engines for more than 20 years , said Roush
.In the very near future , as much as 30 percent of exhaust gas could be circulated back through the diesel engine in an effort to reduce nitrogen oxide emissions.This same exhaust gas also contains significant quantities of sulfuric and nitric acids , which can cause major corrosive wear problems when introduced back into the engine..
Managing Corrosive Wear
Acidic components that have been introduced back into the engine oil are primarily managed by alkaline detergent additives.
But , according to Roush
, there is a limit on the amount of TBN that can be used in an engine oil.TBN provided by alkaline detergents also contributes to oil sulfated ash , which at very high levels , can cause engine operational difficulties such as valve guttering.If enough basicity cannot be built into oil formulations to combat EGR acids , the only option a maintenance manager has is to reduce drain intervals , he
has conducted millions of miles of field tests measuring the effects of corrosive wear , but none of these tests have been done on engines fitted with EGR.We expect to begin field tests with EGR-equipped engines shortly , said Roush
.We will need a statistically significant number of used oil samples during field testing before we can begin to get a snapshot of what is happening inside these new engines.Until we accumulate this hard data , we can only speculate about the true damage corrosive wear will have on the engines..
The Bottom Line
Roush feels that soot will remain an issue in new engines , but equipment managers need to be concerned with corrosive wear first and soot management second.
The corrosive effects of EGR could put long drains in jeopardy , said Roush
.Neutralizing acidic elements and managing soot will both be functions of oil chemistry.Used oil analysis will be more important than ever in determining equipment health and optimizing drain intervals.As more field tests are conducted , additional information will be available to help maintenance managers make worthwhile lubricant choices for their fleets..
The Equipment Maintenance Council
) is an individual membership organization comprised of equipment maintenance professionals.Its members are responsible for the purchase , maintenance , employee training , shop facilities , and parts management of leading corporations and government entities that utilize heavy , off-road equipment.