Motoring Q&A: Is Nitrogen Safe in Gasoline?
Q: The other day I stopped at a Shell station and found their higher-octane gas contained nitrogen. I believe that information posted about the gas said nitrogen was an additive. All of the concerns about ethanol levels and what is safe for which cars caused me to wonder about nitrogen. When I was a kid my friends would add nitrous oxide to their hot rods to get extreme performance out of the engines. Blown engines weren’t uncommon. So is this a safe thing and/or even beneficial?
A: Don’t confuse nitrogen as a detergent additive and nitrous oxide, a performance enhancer. When nitrous oxide is exposed to the extreme temperature of a combustion chamber, the nitrogen dioxide molecule splits into separate nitrogen and oxygen atoms. More oxygen allows more fuel to be burned, thus increasing power output of the engine.
Nitrogen has been used as a detergent in gasoline for some time. Its cleaning properties help reduce and remove carbon deposits from intake and exhaust valves. As such, there is benefit to your engine from the use of gasoline with nitrogen additives. And there’s no danger the nitrogen could contribute to a blown engine.
There has been some consumer concern that nitrogen added to gasoline could contribute to higher nitrogen oxide pollution. Remember exhaust gas recirculation, or EGR, valves? By reintroducing a small percentage of exhaust gas to the incoming fuel/air mixture, combustion temperatures were lowered a bit to help reduce nitrogen dioxide emissions. Oil companies tell us that nitrogen added as a detergent does not contribute to these emissions.
Q: We have two vehicles that we drive less than 2,000 miles per year. One is a 2002 Toyota Corolla that sits idle in a cold Minnesota garage six months a year. The other is a 2005 Toyota Sienna van that sits in a hot Arizona garage for the other six months a year. I use 5-30 standard oil in both vehicles. If the oil looks clean, is there a need to change the oil in these vehicles more than once per year?
A: No, I don’t think so. Whether or not the oil looks relatively clean doesn’t really mean much. Remember, motor oil is the engine’s detergent so some discoloration as miles accumulate is completely normal. With so few miles driven annually in each car, the oil’s additive package has not been depleted, meaning the oil is still fully serviceable.
Once-per-year oil/filter changes on my low-annual-mileage vehicles has been my practice for many years.