The Semi-Synthetics Situation

There are also semi-synthetics on the market. As the name suggests, they are products that fall categorically somewhere between a mineral oil and a full synthetic. Now, they are also subject to a new debate.

Chevron Lubricants says it recently conducted benchmark and field testing to determine how its premium conventional heavy-duty motor oil, Delo 400 LE SAE 15W-40, performed against other major oil companies’ semi-synthetics. Test results show, the company says, that Delo 400 LE with ISOSYN Technology was equal to, if not better than, leading semi-synthetics in industry-recognized tests in the areas of wear control, oxidation and deposit control.

“Most heavy-duty semi-synthetics are touted as having superior performance over conventional oils, but that’s largely a marketing effort to persuade customers that the addition of synthetic base oil to an engine oil formulation will deliver a higher level of protection to critical components, thus justifying the extra price,” says Len Badal, commercial sector manager, Chevron Lubricants. “The notion that a semi-synthetic or synthetic blend provides significant benefits over a product like our Delo 400 LE 15W-40 is a myth.” Based on the research and general information provided by several large heavy-duty OEMs, says Badal, the performance benefits of semi-synthetics versus premium formulated heavy-duty engine oils are marginal at best, and typically don’t justify the additional price a customer must pay for them.

Through bench testing, Chevron documented examples of the competitive semi-synthetic performance myths in multiple areas versus its premium formulated Delo 400 LE 15W-40. In these tests, the Delo 400 LE with ISOSYN Technology performed equal to or better than many leading semi-synthetics. In one test designed to look at soot-related wear protection, Delo 400 LE significantly outperformed three of the four semi-synthetics tested, showing between 16- and 41-percent better wear protection in this test. Tests for oxidation and deposit control also showed very good performance results of Delo 400 LE versus the four major oil companies’ semi-synthetic products.

The company also conducted extended drain field tests on a dozen 15-liter Detroit Diesel DD15 engines. In these tests, Chevron claims to have extended drains out to 70,000 miles without filter changes, achieving the long drain intervals normally touted as a benefit of semi-synthetic products. According to the company, one engine was torn down and inspected at 400,000 miles and showed excellent durability and low wear.

Fuel Economy, Too

While fuel economy is not the key metric in transportation construction that it is in long-haul trucks, evidence from the trucking industry suggests synthetics could help construction fleet trucks that run up miles.

Peter Thomson, director of commercial and industrial marketing at Valvoline, notes that, “in addition to oxidative stability and low/high temperature performance, Valvoline has statistically-significant tests conducted by a leading independent laboratory that found fuel economy benefits for on-highway Class 8 trucks – up to three-percent maximum improvement in fuel economy using SAE J1321/TMC RMP 1103, Type II techniques.” Valvoline, says Thomson, “guarantees a minimum of 1.6-percent fuel saving, compared to traditional lubricants, when using our SmartWay accredited synthetic engine and axle oils, Premium Blue Extreme and Syn Gard FE in on-highway applications.”

Shell’s Arcy agrees that on-highway mpg advantages are proven, but there is no data to quantify off-highway miles per gallon advantages of synthetics. “I would anticipate that there’s a benefit there, but I don’t have the data. You see it on-highway, so why wouldn’t you see it off highway?”

Can You Swap Out?

It’s a commonly-asked question: Can you switch from mineral to synthetic? Shell’s Dan Arcy says it’s also one of the great myths that goes back and forth. For example, some customers use mineral oil in summer months and go into the synthetics for the winter months. “You can go back and forth without any issues. It’s a myth. Years ago, there used to be some issues, but now with seal compatibility there is no issue.”

What Are We Talking About?

So, what exactly are synthetics oils?

Valvoline executives point out that there are three categories of base oils that can be given the term:

Group III, which is highly-refined, hydroprocessed mineral oil,

Group IV, Polyalphaolefins or PAO, which is an engineered hydrocarbon-based product derived from natural gas, and

Group V, which are Esters, considered more applicable in industrial lubricants.

All offer chemically-stable and chemically-consistent base oils with high levels of oxidative resistance.