Older Eaton 9sp what type of oil and how much????

90 weight gear oil

 

If your never going to see under 70°. The Eaton recommended synthetic 50W is the best to use. There are many different brands. All the other oils will make it shift sluggish. The problem could be if it does not let the rear shift fast enough and wear the synchro, then gears in the back half. 5 gallon bucket with out PTO. More with PTO

 

I was told that it is 50 wt. Non synthetic is cheaper but synthetic will last longer until next change. Either will work.

 

Don't use 90w you will ruin the spacers between the dogs and gears. Don't overfill it

 

50 wt., synthetic or not is your choice, I like it. The capacity is only about 3 1/2gal.

 

Your best bet is to call a place that is authorized to sell and repair eaton transmissions. I am in Pa and they told me 50 wt. They did not mention anything about differences in temps. They are in Pa also.

You could go on to the roadranger website. I am sure somewhere on there they explain recommended lubricants.

 

Eaton 50W synthetic 5G bucket $187 #PTSN-50W-5G at Fleet Pride. The difference in the synthetic to the regular oil is the cold (under 70°) shifts. It is sluggish, and drags untill it warms up with the regular oil. The price difference is not enough to think about it.

 

Oh my god, our transmissions are ruined