The Tundra has a recommended viscosity of 5W30 but we had gone to 10W30 since our supercharged engine puts a bigger load on the engine’s bearings. This also means that our oil choice has more viscous drag than stock so a change of oil might make a bigger difference.
ZEPRO 0W20 had been formulated based on Idemitsu’s rich history and knowledge of developing the first factory fill 0W20 for Hondas and the Sky Active powered Mazdas. As we stated before, this oil was our power champion in our last dyno test. It was designed for cars using start-stop technology, the feature that shuts off the engine at lights to save fuel.
Since a lot of an engines wear occurs during starts due to the engine running momentarily with low to no oil pressure as it cranks up to speed, the moly works to provide extra film forming lubrication during those times. We figured that the moly would also work great to protect engine parts under hard use and for performance applications. ZEPRO 0W20 is a high-quality synthetic and has the normal full complement of friction modifiers and extreme pressure additives in addition to the moly to provide great lubrication even with the extremely low viscosity.
For our fuel economy test, we first did a baseline test of driving the Civic and the Tundra by driving over 1000 miles of combined city-highway driving, trying to keep the driving cycle consistent in everyday commuting to and from the office. In addition, we racked up over 300 towing miles in the Tundra.
In our baseline, the Civic did 27.2 MPG while the Tundra averaged 12.2 MPG in regular driving and 9.95 MPG while towing.
With our baseline established we changed the oil to ZEPRO 0W20 and drove another 1000 miles on both vehicles and did just over 300 tow miles on the Tundra.
The results were impressive, Civic averaged 28.7 mpg, a 6.7% improvement! The Tundra averaged 13 mpg, a 6.3% improvement! In Towing the Tundra averaged 10.8 mpg for a fuel economy improvement of 8.3%. This is a really impressive gain from just an oil change.
As a control, we put ZEPRO in a new late model Civic for its first oil change, replacing the factory fill oil. In this case, there was no change in fuel economy since ZEPRO is the Honda factory fill.
We also analyzed the value of going to Idemitsu ZEPRO 0W20. When compared to Mobil 1, a typical synthetic oil, Idemitsu’s street price of about $35 for 5 quarts vs $22 for the same quantity of Mobil 1 is definitely more expensive. However, depending on what sort of mileage your car gets, that price difference is made up in 3 to 6 tankfuls of gas. After you go through that much fuel, you are putting money in your pocket as you have amortized the cost difference between the oils and contributing less to pollution if that matters much to you.
We did have some concerns about running such a thin oil in our high performance, hard use Tundra and we did notice a slight difference in a lower hot idling oil pressure on the factory oil pressure gauge but the Tundra seems ok so far after about 3000 miles of use. We were also concerned about an increase of oil burning with the low viscosity oil but we have not seen an increase in oil consumption on either vehicle.
With great gains in both power and fuel economy, we are very impressed with Idemitsu ZEPRO 0W20. We can definitely recommend it for any late model car designed for low viscosity oil. For older vehicles, as long as oil pressure can be maintained, ZEPRO would also be a great oil to consider.