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Marc1 · 10-08-2019, 14:33

Hi there.
I changed the oil in my MG360 twin disk transmission with ATF after calling Nanni for advise, yet later found out that Twin Disk states sae 30. When I pointed this contradiction out to Nanni they told me that Twin Disk had changed their recommendation from SAE 30 to ATF.

The lubricant plate is blank.

Does anyone here know the real/full story in relation to this?
Your reply is appreciated.

model 10 · 10-08-2019, 16:40

Our Paragon uses either oil. I notice little difference, so now I top off with engine oil. Trans fluid is about 10wt hot or cold. 30wt is that cold, then it warms up.

**a64pilot** · 10-08-2019, 17:53

ATF is about 10W, it’s very similar to hydraulic oil with an excellent detergent package, automatic transmissions are of course hydraulic beasts with bands and clutch packs, so ATF is excellent for a marine transmission with dual clutch packs like my KBW20.
Dexron and Ford fluids used to vary slightly, the Dexron used to be slipperier, and when we built transmissions years ago for drag racing we ran ford fluid in them, but it seems now that fluids exist that meet both requirements.

Marc1 · 10-08-2019, 17:54

Yes, there is substantial difference between one oil and the other.
A search brought up a couple of post confirming ATF for this particular transmission.
I find it odd that Twindisk if they did change their mind did not publish this change.
I think I'll email them.

Marc1 · 10-08-2019, 18:19

PS

I pumped out the old oil, drain plug is not accessible, and came out milky.
Bummer I thought, water in the oil.
THe only way water can come in is from the cooling copper tube that goes through the oil or it's seals.
I put new ATF oil in and run the engine briefly, then pumped the oil out again and replaced.
Oil is now bright red and no signs of contamination.
Would that be the end of it or I may have some sort of slow leak?

**a64pilot** · 10-08-2019, 18:46

Best way to know for sure is to run it and watch it.
It doesn’t take much water at all to turn it into a pink milkshake if ATF or chocolate milkshake if motor oil.
You can of course pressure test the cooler if you have the equipment, but unless I was going on a big trip, I’d just watch it for awhile. Check it after every shutdown, let it sit overnight and it’s possible it could separate out and you may not see the mix, but unlikely.
Once water is emulsified with oil it tends to stay mixed.

capt jgw · 10-08-2019, 18:59

Most gear boxes have a vent, usually in the dipstick/fill cap. If water has ever dripped onto the top of the box, that could be the source of the water.
My engine room has a hatch in the cockpit sole to access the engine, and it used to leak. I knew it was leaking when I found the pink milkshake in my gear box. No oil cooler on the gear so the hatch was the only source of water. Fixed the leak, no more water in the gear.

Reefmagnet · 10-08-2019, 20:25

I would guess the breather, too. I modified mine by fitting length of tube like a 4wd diff breather to make sure dripping water doesnt find it's way in.

AndyEss · 10-08-2019, 21:48

I don’t have an oil cooler, and at the last change, tranny oil was water contaminated. The breather vent is the only source.
I wouldn’t be surprised if even humidity in the air would eventually condense out enough to make the tranny oil water contaminated.
My tranny manual says fill with 2x the volume of tranny oil with diesel to clean, run 10 minutes shifting back and forth reverse to forward, drain diesel and refill with correct amount of ATF only.

**GordMay** · 11-08-2019, 03:38

Twin Disc MG-360 Mechanically-operated conical clutches - as of 2006
Oil quantity 0.81 liter
Oil type SAE 20 or 30
➥ https://www.glpower.com/files/twin-d...ions/MG360.pdf

2004 (revision 4) Manual
NOTE: Some MG6000 series transmissions built before 2002 do notutilize a lubrication data plate. See Section 2.4 for oil recommendations.
CAUTION: Multi-viscosity oils (i.e. 15W-40 etc.), automatic transmissionfluid (ATF) and synthetic oils are not approved for use in TwinDisc marine transmissions without written approval from TwinDisc.
➥ https://www.marind.ca/medias/pdf/pro...ors_manual.pdf

Marc1 · 12-08-2019, 00:44

Yes, I saw that Gord, and that was why I contacted Nanni.
Now I have written to Twindisk but so far no reply. Not holding my breath.

capt jgw · 12-08-2019, 06:50

The Hurth manual says that if you do a winter layup, fill the gear to the top with atf then drain back to normal level when you recommission. That would prevent condensation but I doubt many people actually do it. That may have been part of the problem with my boat, I didn't have the manual and finally read one after I found the watery oil.

FPNC · 12-08-2019, 12:35

The TwinDisc 360 is the same transmission as the Technodrive TMC60. These are cone clutch mechanical gears. The manual referenced by GordMay was for much larger multi disc clutch hydraulic units. The small Mechanical units have used ATF for a very long time. Use regular non synthetic ATF, don't overfill, change it once a year.

Marc1 · 12-08-2019, 14:12

Just to clarify FPNC ... mg360 is a hydraulic gearbox as opposed to a mechanical like Paragon that needs a one meter long lever to operate.
I see that the website classifies the gearbox as mechanically operated because to change gears you must push the little lever with a cable or rod. However the internals are hydraulic.
Or so I remember (vaguely)

Sailmonkey · 12-08-2019, 14:16

Quote:

Originally Posted by Marc1

Just to clarify FPNC ... mg360 is a hydraulic gearbox as opposed to a mechanical like Paragon that needs a one meter long lever to operate.
I see that the website classifies the gearbox as mechanically operated because to change gears you must push the little lever with a cable or rod. However the internals are hydraulic.
Or so I remember (vaguely)

It’s not hydraulic. I’ve got one, it uses atf.