Being that my PS whines I thought it a good idea to verify something that isn't explicitly labeled just in case they were actually arbitrary marks.

 

It is just a dipstick, all dipstick measure in the same fashion. Whether it is oil, transmission, or PS, you have a min and a max mark.

Primary function is measuring the depth of the fluid. It should be parked on a level surface and the fluids would tend to expand with heat as any fluid would.

The whine is most likely the bearings in the pump. I did read that PS Fluid will cause such problems with these since they were designed to use Transmission fluid. If it was operated with low fluid level, that could also contribute to the whine. Lots of PS pumps whine.

I do not know what the differences are in the properties of the two different fluids. I have a bottle of STP PS Steerring Fluid I bought right after buying my Discovery befor I learned it uses ATF. I did not use the STP fluid because of that. It has been on my shelf since 2006.

 

Friction modifiers.

Me too. I did all the same. Bought two "cause it was raining fluid". Put one in and still have the other.

 

In an effort to redress an episode of horrific stupidity....