Changing transmission oil type?

[evanwilson]

I am planning on changing the transmission oil in my B5100. It currently has gear oil in it, presumably the recommended 80w/90 variant. However, some service manuals reccomend UDT. My question is this, can I swap to UDT when there will still be residue of gear oil in the system?

I actually plan on using Mobil 428, which is listed as a replacement to Kubota UDT. My main reason for wanting to swap is the fact that there is a barrel of 428 in the yard already. I also want to fit a trailer tipping valve to the tractor at some stage, and using 428 will have the tractor compatible with any trailer used by any of our tractors.

 

[TheOldHokie]

I am planning on changing the transmission oil in my B5100. It currently has gear oil in it, presumably the recommended 80w/90 variant. However, some service manuals reccomend UDT. My question is this, can I swap to UDT when there will still be residue of gear oil in the system?

I actually plan on using Mobil 428, which is listed as a replacement to Kubota UDT. My main reason for wanting to swap is the fact that there is a barrel of 428 in the yard already. I also want to fit a trailer tipping valve to the tractor at some stage, and using 428 will have the tractor compatible with any trailer used by any of our tractors.

Drain and refill - it will be perfectly fine.

Dan

 

[evanwilson]

Drain and refill - it will be perfectly fine.

Thanks for clearing that one up Dan. Great to get a direct and sure answer

 

[RalphVa]

Yes, drain and refill. The gear oil is probably about 30w oil vs. about 20w for the replacement you've planned (if engine oil ratings are used). Gear and hydraulic oil is rated at 104 F vs. 212 F for engine oil.

I once had a 1964 Valiant that specified either ATF or gear oil in the manual transmisssion. I changed it out after some miles to gear oil. Could hardly shift it when cold. Almost immediately drained and refilled with ATF (which is about 10w).

 

[TheOldHokie]

Yes, drain and refill. The gear oil is probably about 30w oil vs. about 20w for the replacement you've planned (if engine oil ratings are used). Gear and hydraulic oil is rated at 104 F vs. 212 F for engine oil.

I once had a 1964 Valiant that specified either ATF or gear oil in the manual transmisssion. I changed it out after some miles to gear oil. Could hardly shift it when cold. Almost immediately drained and refilled with ATF (which is about 10w).

Ralph!!!
SAE gear oil grades are defined at 100C just like engine oil.
Hydraulic oil uses ISO viscosity grading system which is defined at 40C.

Mobilfluid 428

Grade: SAE 10W-30
Density @ 15 C, g/ml, ASTM D4052: 0.866
Kinematic Viscosity @ 40 C, mm2/s, ASTM D445 : 59
Viscosity Index, ASTM D2270: 141
Flash Point, °C, ASTM D92: 243
Pour Point, °C, ASTM D97: -48

Dan

 

[RalphVa]

No. Gear oils are at 104 F.

 

[TheOldHokie]

No. Gear oils are at 104 F.

I have no idea what you think the table you posted demonstrates. The governing specifications are SAE J300 for engine oil and SAE J306 for gear oil. The gear oil viscosity grade requirements table below can be found in the SAE J306 specification. If you doubt the accuracy of that table you can purchase your own copy of the full document straight from the SAE for $44. Or simply ask Google to show you "SAE J306" ......

J306_201708: Automotive Gear Lubricant Viscosity Classification - SAE International

This SAE Standard defines the limits for a classification of automotive gear lubricants in rheological terms only. Other lubricant characteristics are not considered.

www.sae.org

Dan

 

[RalphVa]

The Mobil 428 is a dead center match to JD's hy vis hydraulic oil. I always used low vis here in Va, but hy vis should be okay if the winters do not get too cold.