I often wonder how many alternative fueled school buses would be around if emissions-reduction initiatives had not been put in place and interpreted the way they have been.


To better understand the comparative fuel consumption between the two most popular school bus fuels, I contacted a user of numer- ous propane school buses to obtain actual operating mpg numbers and to compare “new” diesel miles per gallon to new LPG. Te result is experience has the Type C LPG coming in at 4.6 mpg and the Type C diesel at 8 mpg. If you do the math, based on the miles you travel, you will see that propane’s consumption fuel-cost benefit is dependent on continuing alternative fuel tax credits, How much longer will this last? Another frequently mentioned benefit is engine oil cost. Since CNG and LPG are both gases with little piston ring blow by of combustion by-product, it is said that using those fuels rather than


diesel will have little effect on engine oil contamination, so extend- ing change intervals is a perceived benefit. I always caution maintenance operations to never exceed the


OEM required oil change interval. Even with an engine oil anal- ysis in hand, it is unlikely that any of the engine manufacturers will change their warranty to accept your extended interval. Oil continues to be the cheapest tool in maintaining engine life in any garage. 


Te opinions expressed are those of the author based on his expertise and do not necessarily reflect those of School Transportation News magazine..


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