This article was updated May 18, 2021.
Aftermarket additives are a popular off-the-shelf item at truck stops and parts counters, but many of the necessary additives already are formulated in the diesel engine oils directly from the supplier.
“Engine oil absolutely has to have additives in it,” said Stede Granger, technical services manager for Shell Lubricants. Granger said engine oil basically consists of two components: the base lubricant stock and the additives that support it.
“Engine oils are probably the most complicated, the most balanced and typically have the most additives of any of the oils we make,” he said. “Oil manufacturers spend millions of dollars to develop the right additive package.”
Engine oil is produced with one intention – to reduce friction – and Rob Howes II, executive vice president for Howes Products, said this is accomplished through the use of several common ingredients, including zinc, calcium, phosphorous and sulfur.
Howes said if an oil additive is used, it is important that it contain these base ingredients. “Otherwise, by swapping the additive in for a quart or gallon of your conventional oil, you are effectively degrading the oil,” he said. “On the other hand, overuse of these ingredients, while great for the performance of the oil, can cause other problems, such as harming emissions systems or excess pollution.”
Darryl Purificati, OEM technical liaison for Petro-Canada Lubricants, said the additive package of a heavy-duty engine oil makes up approximately 10-20% of the lubricant itself and is balanced to meet OEM requirements while optimizing the engine oil’s performance.
