Q: What is the best oil for engine and gear oil. RPM is stuck at 4000 and not going up. I'm in a Honda Zest car.

Hi there. The best oil to use on any Honda 2005 or newer is Mobil 1 high life or Valvoline. That will ensure that you have the correct type of oil for the best performance for your vehicle. The issue with the rpm maxing out at 4000 is the computer could have the vehicle in limp mode. This determines when the engine is accelerated. If the engine is accelerated in park or neutral, then the computer will limit the engine’s rpm to prevent any problems if the transmission was to engage a gear.

If the transmission is in gear and the rpm’s are low, then the computer has the engine in limp mode for a transmission issue. Check the transmission oil level and check all of the harness connections to the transmission. If everything is in good order, then there could be an issue with the transmission. If you need further assistance diagnosing the high RPM, then seek out a professional, such as one from YourMechanic, to help address this.