Hi, Cronk.
Here's what I've picked up with my experience with an MF35. It's very similar to your 9N.
I have found that the 134D oil is a universal Trans/Diff/Hydro(TDH) oil also known as Hytrans, Permatran, etc.
But it has a viscosity roughly equal to a 10w20 engine oil, but that grade doesn't exist.
It's way too thin for the older machines and their somewhat worn hydro pumps. Works great in winter cold for moving snow, but the pumps don't perform well in summer heat with it. It is yellow metal safe.
I used it and that was my experience.
I switched to the Dentax that you mentioned. Great for the summer, but in the winter I need to let it warm up a bit and then it's ok.
Nowadays, the folks at ytmag report that 15w40 engine oil, makes a good all season alternative. Thin enough for the pump to easily pump it in winter, but thick enough for the pump to keep working well in the summer.
Apparently, a lot of people have been using it in these old machines with no trouble. It's yellow metal safe. Don't forget that engines use bearings that have copper in them.
One guy said he puts in the 80w90 GL1 and for the winter and added a bit of 10w30 motor oil to thin it just a touch and it works well all year.
I posted about this here to, and I think I'll drain out 1 gallon and add some 10w30, rather than dump it all for 15w40.
Hope this helps.
Here's what I've picked up with my experience with an MF35. It's very similar to your 9N.
I have found that the 134D oil is a universal Trans/Diff/Hydro(TDH) oil also known as Hytrans, Permatran, etc.
But it has a viscosity roughly equal to a 10w20 engine oil, but that grade doesn't exist.
It's way too thin for the older machines and their somewhat worn hydro pumps. Works great in winter cold for moving snow, but the pumps don't perform well in summer heat with it. It is yellow metal safe.
I used it and that was my experience.
I switched to the Dentax that you mentioned. Great for the summer, but in the winter I need to let it warm up a bit and then it's ok.
Nowadays, the folks at ytmag report that 15w40 engine oil, makes a good all season alternative. Thin enough for the pump to easily pump it in winter, but thick enough for the pump to keep working well in the summer.
Apparently, a lot of people have been using it in these old machines with no trouble. It's yellow metal safe. Don't forget that engines use bearings that have copper in them.
One guy said he puts in the 80w90 GL1 and for the winter and added a bit of 10w30 motor oil to thin it just a touch and it works well all year.
I posted about this here to, and I think I'll drain out 1 gallon and add some 10w30, rather than dump it all for 15w40.
Hope this helps.