05-12-2022, 12:32 AM
Just a quick update.
Installed the 15w40 T6, full synthetic.
After running the dealer-installed GN4 10W40 for a season and averaging about 40 mpg, with an all time high of 46 mpg once, I was very pleased to see my mileage has improved to 50 mpg with my first full tank running the 15w40.
The old Honda GN4 10w40 had about 3500 miles on it, and had the viscosity of coffee when it came out.
I'm interested to see if the mileage will continue to be this good or if it's just a fluke.
Even comparing to my previous record of 46 mpg on the GN4, 50 mpg is almost a full 10% improvement. Compared to my average of 40 mpg, it's better than 20%!
I am not sure, but it's possible that the engine is a little louder with the 15w40 compared to 10w40. This could simply be an expectation bias as I anticipated that the 15w40 might be louder, and I was fully prepared to dump out the 15w40 immediately if the mileage was poor.
Luckily the mileage improved, so I will be sticking with the 15w40 for at least a little while longer.
I wanted to share my experience as there seems to be a bit of confusion on this topic, and even some fear mongering when it comes to using non-Honda oils.
I know a lot of people here use the 5w40 T6 instead of the 15w40. I picked the 15w40 due to it's improved sheer resistance, and the fact that I rarely ride below 32F, and never ride below 22F.
If the 15w40 had caused worse mileage, I was considering the 10w30 Rotella T4, a semi synthetic at the exact weight spec'd in the owners manual. If I was in a colder climate than Texas the 10w30 might be my go-to oil.
Anyhow, so far so good with the 15w40 T6.
Installed the 15w40 T6, full synthetic.
After running the dealer-installed GN4 10W40 for a season and averaging about 40 mpg, with an all time high of 46 mpg once, I was very pleased to see my mileage has improved to 50 mpg with my first full tank running the 15w40.
The old Honda GN4 10w40 had about 3500 miles on it, and had the viscosity of coffee when it came out.
I'm interested to see if the mileage will continue to be this good or if it's just a fluke.
Even comparing to my previous record of 46 mpg on the GN4, 50 mpg is almost a full 10% improvement. Compared to my average of 40 mpg, it's better than 20%!
I am not sure, but it's possible that the engine is a little louder with the 15w40 compared to 10w40. This could simply be an expectation bias as I anticipated that the 15w40 might be louder, and I was fully prepared to dump out the 15w40 immediately if the mileage was poor.
Luckily the mileage improved, so I will be sticking with the 15w40 for at least a little while longer.
I wanted to share my experience as there seems to be a bit of confusion on this topic, and even some fear mongering when it comes to using non-Honda oils.
I know a lot of people here use the 5w40 T6 instead of the 15w40. I picked the 15w40 due to it's improved sheer resistance, and the fact that I rarely ride below 32F, and never ride below 22F.
If the 15w40 had caused worse mileage, I was considering the 10w30 Rotella T4, a semi synthetic at the exact weight spec'd in the owners manual. If I was in a colder climate than Texas the 10w30 might be my go-to oil.
Anyhow, so far so good with the 15w40 T6.