Diesel Motor Oil 2019 Test: Which Brand Wins?
In our 2019 test we compared 2 diesel motor oil options head to head. Shell Rotella T6 came out on top. See the measured results, the runner-up, the budget pick, and a link to the full test video.
Shell Rotella T6
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Chevron Delo 400
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The quick take
The short version of why each pick lands where it does, built straight from the measured results.
“in my opinion based upon my testing along with the oil labs information t6 is a better oil”
The measured results
Every number below is read straight from the test. Products are listed in the order they finished.
All measurements (4 more)+
Evaporative Loss Heat Test
- 1Shell Rotella T6 5W-40 synthetic
started at 430.13 g and finished at 423.71 g after 2 hours at 410 degrees Fahrenheit, a loss of 6.42 g, less evaporative loss than Delo
- 2Chevron Delo 400 full synthetic 5W-40
started at 411.29 g and finished at 402.84 g after 2 hours at 410 degrees Fahrenheit, a loss of 8.45 g, more evaporative loss than T6
Lubricity Wear Scar
- 1Shell Rotella T6 5W-40 synthetic
came out ahead of Delo with a 3 percent smaller wear scar
- 2Chevron Delo 400 full synthetic 5W-40
performed very well but with a slightly larger wear scar than T6, about 3 percent larger
Cold Oil Flow Test
- 1Shell Rotella T6 5W-40 synthetic
won both new and heat cooked cold flow races at minus 40 degrees Fahrenheit; new T6 finished first, cooked T6 finished second, ahead of both Delo samples
- 2Chevron Delo 400 full synthetic 5W-40
lost both new and heat cooked cold flow races at minus 40 degrees Fahrenheit; new Delo finished third, cooked Delo finished fourth (last)
Oil Lab Analysis
- 1Shell Rotella T6 5W-40 synthetic11 percent
higher detergent dispersant content than Delo, 31 percent higher anti wear additive package including phosphorus and zinc, and a slightly higher total base number than Delo
- 2Chevron Delo 400 full synthetic 5W-40
lower detergent dispersant content, lower anti wear additive package, and a slightly lower total base number than T6 per the side by side oil lab report comparison
How it was tested
- used oil filter and filter media visual inspection for corrosion and debris after extended time in service
- independent oil lab analysis of used oil samples for viscosity, contamination, and total base number
- lubricity or film strength wear scar test comparing used oil to new oil
- evaporative loss (Noack-style) heat exposure test at 410 degrees Fahrenheit for 2 hours
- lubricity wear scar test on the heat cooked T6 versus Delo oil
- cold oil flow race at minus 40 degrees Fahrenheit using both new and heat cooked oil
- independent oil lab analysis comparing T6 and Delo detergent dispersant content, anti wear package, and total base number
“in my opinion based upon my testing along with the oil labs information t6 is a better oil”
