JD low vis. hydro oil

[neilw]

I know the JD purists will not like this. However, I'm looking for a replacement for my JDM J20D Low Viscosity Hydraulic Oil. My 790 operators manual calls Low Viscosity the prefered oil of choice. However, if unavailable Hy-Gard JDM J20C can be used.

I think my question is a two parter.

1: What the heck is Low Viscosity Hydraulic Oil anyway? You know what I mean whats the SAE weight or ISO number.

2: In Central Texas do I really need a low viscosity oil? I would have to have a very compeling reason to operate the tractor when its much below freezing. In ten years of country life (a Ford 8N, MF 135 and now a JD 790) that has never happened.

 

[Old_Wanker]

Heres a few links you may want to try ...

<A target="_blank" HREF=http://www.amsoil.com/products/ath.html>Amsoil ATH</A>

Texaco TDH

<A target="_blank" HREF=http://www.mobil.com/mobil_productdata/automotive/transmission/fluid424.html>Mobil</A>

Some of the SAE and API figures are given in these links. This is a common JD spec oil. Id not bother with the low viscosity stuff down where you are. Even if you do get that rare cold spell let the tractor warm up for a while before doing any heavy work, perhaps drive it around a bit to get the transmission oil moving and warmed up and you wouldnt have any problems.

Best of luck

 

[GlennT]

I'll second what Joe said; not because I have any petroleum expertise, but because of my experience with our local dealer. I live south of you in Central Texas and our John Deere dealer doesn't even carry low-visosity transmission/hydraulic-system oil. When I asked about this I was told that it isn't needed in our warm/hot climate.

 

[neilw]

Thanks Joe and Glynn for your input. Since I posted this question I received and reviewed the Technical Manual and it has a temp. chart showing Low-Vis Hy-Gyrd only usable up to 86f.

Additionally I just returned from Idaho where I spoke to a JD dealer in Nez Perce, Id (sp) who did not recommend the use of low-vis hydro. during an Idaho high plain summer.

I'm going to use regular hydro J20C fluid from now on.

Still I wonder why my JD dealer recommends a fluid that clearly is out of temp. range for my location.