You can certainly use rotor oil for both the interior and exterior; with that said, as the external points of contact (the spindle, linkage joints, paddle assembly) are more exposed a heavier weight oil may sit on the surface better and provide longer lasting protection (plus it is less likely to run off on ones clothing... ;). )

The Hetman 13 is designed more for the exterior bearing and linkage surfaces of the valve as it is a slightly heavier, thicker oil vs. the 11-12 which is thinner and designed more for valve interiors. To answer your question, I wouldn’t expect using the 13 on the interior to damage your valve at all. The bigger question for me is the performance; if your valve moves quickly and freely with the 13 I don’t know if I would make a change. However, if you wanted to see if a thinner oil would increase speed it may be worth experimentation...

Normal meaning piston valve oil and/or petroleum-based? Piston valve oil can work but it tends to be a lighter weight and thus will need more frequent application; it also may not provide the same protection as rotor valve oil. Whether one uses petroleum or synthetic I would recommend utilizing rotor-specific oil to help ensure the proper protection...

Thankyou this helped a lot!!!

It is a very fair point, and certainly an issue we have encountered as well. In general I think the concept is trying to keep things as easy and safe as possible, especially with younger students in mind, and the idea of having the be relatively secure, and being able to keep it on the same surface for both the internal and external oiling. With that said it is only one approach and we are certainly open to the wisdom of a master like yourself :)

First guess (and I am not a great tech) is that the valve has a touch of play inside the casing and is making noise as it moves along the spindle axis. It sound like you already did but I would check the screws on the stop arm plate on the back of the valve casing, along with the screw on the spindle to make sure there is no movement; I would also check the bearing plate under the valve cap to make sure that it is fully seated in the casing (if not, I would recommend seeing a tech to make sure the plate is seated and the valve is aligned properly.). Assuming you don't find anything here I would check the linkages for excess play and movement; if you hold the valve spindle still and try to activate the lever there should be no movement. If you notice a bit of play a thicker linkage oil may help; if there is a lot of play one of the linkage arms may need to be tightened or one of the ball joints may have excess wear and may need to be replaced. Just a cursory guess; if none of these look like the culprit I would absolutely recommend having a tech in your area take a look. Good luck and let me know how things turn out!

Absolutely! I usually like to use the 12 for rotors and the 11 for axial flow valves; The 12 often seems to be just a little thick for the tight tolerances and larger surface area of the axial flows...