“Tere is a lot of chemistry occurring in all the oils that are used to lubricate today’s modern diesel engines. As we approach another milestone in engine design and lubricating oil technology, we need to be aware that they are complicated mixtures that are in balance with one another and need to be respected.”
nologies. Specifically, these “next-generation oils” will be formulated with lower viscosities than currently used to meet the demand on engine performance for increased fuel economy and reduced emissions, all without sacrific- ing protection against engine wear.
API FA-4
Te American Petroleum Institute (API) has estab- lished its FA-4 performance specification exclusively for most 2017 and newer diesels, due to the oil technology needed to meet certain engine designs’ low-viscosity requirements. API FA-4 oils cannot be used in diesel engines made prior to 2017. However, it is important to know that FA-4 may not be recommended for all new 2017 engines. You must check with your bus engine manufacturer for which oil to use.
API CK-4 For some 2017 model-year and older diesels, where the engine manufacturer would not recommend the FA-4 specification, the API has established its CK-4 specifi- cation. Tis is a “Backward Compatible Formula” that can and should be used to replace the old CJ-4 oils you probably now use. It provides improvements over the old CJ-4, most notably protection against catalyst poisoning, particulate filter blocking and engine wear. Since CK-4 is “backward” compatible, you should be using this type of API designated oil in your older buses now. While the challenge of having to stock two new diesel oil specifications may initially complicate things, make sure all dispensing equipment is properly labeled with the product name, viscosity grade and API designation to pre- vent the wrong oil from finding its way into your engines. Note that model-year recommendations are a guide- line; always be sure to check the manufacturer’s owner’s manuals for specific requirements, since in some cases the bus manufacture year may not match the engine model year. Managing these oil upgrades properly will help school
districts and contractors reduce maintenance costs and extend equipment life, which will help them to oper- ate within budgets that demand peak reliability and efficiency. Contact your oil supplier as soon as possible to learn more about how this will impact your oil supply program, inventory and cost. You should always pay close attention to any change to the school bus manufacturer’s engine specific rec- ommended oil requirement and change interval. Please remember that manufacturers base oil change intervals on engine operating hours, miles travelled and fuel consumed. Do not risk your engine warranty coverage by extending oil changes beyond the original equipment manufacturers’ guidelines. Remember, there is a lot of chemistry occurring in all the oils that are used to lubricate today’s modern diesel engines. As we approach another milestone (with many more to come) in engine design and lubricating oil tech- nology, we need to be aware that they are complicated mixtures that are in balance with one another and need to be respected. Engine manufacturers’ lubrication engineers will always tell you that mixing of different oils and adding additional engine additives should be avoided. ●
Robert T. Pudlewski is STN’s technical editor and a nationally recognized expert in school bus maintenance practices and technology. He is also an inductee into the NSTA Hall of Fame. Contact him at
bpudlewski@roadrunner.com.
www.stnonline.com 53
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