Shirl wrote:
Matt Whiting wrote:
Engines have vibration and resonances that vary with RPM. Running at a
constant RPM for long periods of time causes a certain wear pattern on
certain parts. Varying RPM over time induces different vibration an
part resonances and spreads the wear over different areas. This isn't a
bad, bad, bad thing.

My mechanic echoed this also. I was told even in cruise that it's a good
idea to vary the RPMs every 10 minutes or so.

I believe that is a good idea also. Constant RPM is great for engines
that will ALWAYS run at constant RPM (stationary generators, etc.).
However, for engines that must run across a range of RPMs, I believe it
is better to operate them across that full range as often as practical.

Matt