Twin Disc MG5061A Lubrication

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KevinCT

Veteran Member
Joined
Jul 29, 2015
Messages
36
Location
USA
Vessel Name
Neon Moon
Vessel Make
Ocean Alexander 480 Classico
I need help understanding exactly which lubrication is best for Twin Disc MG5061A gears. The manual has a notation to see the builders plate on the gears for specific lubrication. There is a handwritten notation in the book that says CF-4 30 wt. I know there are detergent and non-detergent oils, straight 30 wt, and so forth. I want to be sure I get the right lubrication. Can anyone help me, please?
 
Is the builder's plate on your TwinDisc missing? If you have twins, is it missing from both?? It really is best to use whatever it says on this plate if they are still mounted
 
The builders plates are there -- "Oil Service Class - Use S.A.E. API Service class CD Engine Oil Certified by vendor to pass TO-2 Oil Test"

"Also approved are S.A.E. API Service Class CC Engine Oil MIL-L-2104 B, and Transmission Fluid Type C-3. Viscosity: Steady Operation 15-=185 S.A.E. 30, 175-210 S.A.E. 40"

I find all this confusing.
 
The CD or CC spec shows the tranny does not require much detergent in the oil.

That is good as there is more lube oil and less additive package .

My guess is the 40 wt would be normal for 175F -210F use in most non winter situations.

A laser thermometer will tell after a couple of hours just how hard / hot the tranny is working.
 
The plate is saying that if the operating temperature of the transmission oil is in the range -15F to 185F, use straight (not multi) 30 wt oil; go up to 40wt only if your standard op temps are 175-210F.


This has been discussed often on BoatDiesel, where Tony Athens makes the point that operating temps of transmissions are typically MUCH lower than engine oil temps. Straight 30wt oil is usual in applications like our boats. I note that is just what the annotation in your handbook indicates
 
On some engine/gear packages, the gears are cooled by engine coolant not sea water, so gears there run a good bit hotter. Nothing wrong with them running 190F, actually keeps moisture at bay and coolers live much longer. Those are the only ones I'd consider running 40wt.
 

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