On the horizon: API CK-4 synthetic diesel engine oils

There are still some pockets of resistance to synthetic oils in the heavy duty motor oil market, perhaps a misconception that they aren’t as good as the “real” thing. 

What is a synthetic oil, anyway? Simply put, it is an oil formulated with a synthetic base instead of a mineral base. It is still a hydrocarbon product and still uses additive chemistry to enhance particular properties. It is also worth noting that engine OEMs have never restricted the use of synthetic oils and do not distinguish between synthetics and conventional based engine oils—so long as the finished products meet their performance specifications. 

As synthetic engine oils have become more commonplace, the definition of “synthetic” has begun to evolve. A majority of oils on the market today have at least some synthetic element to them. In particular, synthetic blends that meet the same OEM standards as conventional oils have become increasingly commonplace among SAE 10W-30 oils.

A synthetic base is typically used to produce a finished engine oil that has superior low-temperature properties. Synthetic based oils have a high viscosity index that allows producers to make oils that remain fluid at low temperatures for better cold weather start-up. These properties also contribute to fuel economy. At higher temperatures, synthetics exhibit better oxidation stability which can help extend drain intervals and less volatility, which reduces the chances of evaporation and can improve oil consumption. 

Synthetics are definitely on the new API category CK-4 oil roadmap. For the official category license date – December 1, 2016 – major lubricant producers focused their initial efforts on making sure the most in-demand, highest volume diesel engine oils would be available at the earliest date. CK-4 synthetics, however, require more extensive and more specialized testing, so their rollout will be more gradual. At Chevron, we’re in the final stages of development of an SAE 5W-30 and SAE 5W-40 synthetic oil within our Delo® 400 product line, with availability targeted for later this year—stay tuned!