The rates at which PWM can operate are meaningless to the operation of a solenoid valve, and oil flow, in my opinion. I could be wrong, but it seems like the so common trick of bamboozling people with terminology that seems to make sense but is really not applicable. Kind of like saying your computer utilizes "turbo" technology. What the F#%% does that mean?
Turbo comes from the old days when plenty of software (especially games, but also office sw) was coded with certain expectations of the processor's specific clock rate.
The "turbo" button just made the cpu run at its actual full speed, which "non turbo" essentially a compatibility mode. or, surprisingy, what i just wrote but opposite: "turbo" indicated
slower clock speeds. You'll have to ask a marketing person how this makes sense
Today, "turbo" features are about heat. a modern cpu has FAR more functionality than could be run at once/continuously and stay inside the thermal envelope (both cooler capacity, and temp gradient inside the chip package itself). most functions are not working at the same time. similarly, higher clock rates go faster (duh) but also consume more power == produce more heat. turbo mode inside a cpu today plays with these pararmeters (esp clock speed) to make the most of the perf options available.
Tl;dr - definitely marketing speak, but the underlying functionality IS doing something helpful for the user.
Similarly, PWM _is_ how the underlying solenoids are controlled. But there is a fair amount of software/firmware on top dictating exactly how and when (reading feedback, etc), and some analog filtering below to customize the transfer function between digital input (pwm) and analog output (spool movememt).
[Edit for completeness - this
can be done entirely with analog electronics; at one point in time it was done this way. However, with modern / cheap microcontrollers and sensors, given a certain (engineering +test + hardware)
number of dollars, digital controls are typically the stronger choice]
