Originally Posted By: Gokhan
Originally Posted By: Vlad_the_Russian
- Really enjoying the smoothness of throttle response in the lower RPM range. Feels like the engine gained some torque. Can't explain why... Better ring seal?... BUT hate the slight HP loss in the upper RPM range. Very minor, but the loss is there.
According to the fundamental curve of lubrication -- Stribeck curve -- minimum oil-film thickness (MOFT) and friction increase with viscosity (n [eta]) and RPM (v) and decrease with engine load (P) in the hydrodynamic region. Therefore, it makes sense that you see more effect at high RPM than at low RPM. However, I don't know how you control RPM for a given engine load if you don't have a manual transmission.
It makes little or no sense that the engine gained HP at low RPM with thicker oil. The only way that would happen is that your engine is running in the boundary region -- metal-to-metal contact -- and about to fail. I take the more plausible explanation that it's merely a subjective, psychological observation.
Your MPG didn't change going to a thicker oil? Given how impossibly difficult it is to measure MPG, no one here would believe that.
Toyota engines can tolerate pretty much any viscosity. However, as most people here said, you will gain no benefit from running such an unnecessarily thick oil. Your oil temperature and pressure will be unnecessarily high. You will lose HP and MPG regardless of RPM. Wear-protection benefits? You will be lucky if thicker oil actually doesn't end up producing more wear. Simply run the recommended oil for the most HP, MPG, and probably the longevity as well.
Someone here posted that all engines with a carburetor must run 20W-50. I laugh at such old wives' tales posted on the Internet. I run 0W-20 in a 1985 engine with a carburetor with no problems. Fuel dilution? I've never experienced it.
Here we go again
Originally Posted By: Vlad_the_Russian
- Really enjoying the smoothness of throttle response in the lower RPM range. Feels like the engine gained some torque. Can't explain why... Better ring seal?... BUT hate the slight HP loss in the upper RPM range. Very minor, but the loss is there.
According to the fundamental curve of lubrication -- Stribeck curve -- minimum oil-film thickness (MOFT) and friction increase with viscosity (n [eta]) and RPM (v) and decrease with engine load (P) in the hydrodynamic region. Therefore, it makes sense that you see more effect at high RPM than at low RPM. However, I don't know how you control RPM for a given engine load if you don't have a manual transmission.
It makes little or no sense that the engine gained HP at low RPM with thicker oil. The only way that would happen is that your engine is running in the boundary region -- metal-to-metal contact -- and about to fail. I take the more plausible explanation that it's merely a subjective, psychological observation.
Your MPG didn't change going to a thicker oil? Given how impossibly difficult it is to measure MPG, no one here would believe that.
Toyota engines can tolerate pretty much any viscosity. However, as most people here said, you will gain no benefit from running such an unnecessarily thick oil. Your oil temperature and pressure will be unnecessarily high. You will lose HP and MPG regardless of RPM. Wear-protection benefits? You will be lucky if thicker oil actually doesn't end up producing more wear. Simply run the recommended oil for the most HP, MPG, and probably the longevity as well.
Someone here posted that all engines with a carburetor must run 20W-50. I laugh at such old wives' tales posted on the Internet. I run 0W-20 in a 1985 engine with a carburetor with no problems. Fuel dilution? I've never experienced it.
Here we go again