Fluid for Gear ATF or SAE40

[Keith Callaghan]

All, first a big thank you to Tony and all the people on this forum. I have a 6bta – 270 that with the knowledge I have gained from this website and the people on this forum I have been able to understand and service and keep happy…. This cannot be said about by marine gear. It is a rebuilt unit that is a Twindisc. Well at least Twindisc is embossed in the casting. I have no idea what model number it is nor any info about it. There is no nameplate or any lubricant info. The mechanic who changed out the old gear for this gear is Thai (language isue) and I would not trust anyway because the old gear should have never been taken off to begin with. He basically sold the previous owner a bunch of lies to get money from him and increase the speed of the boat drastically. Well it is a slow semi-displacement trawler.. and short of adding a rocket engine it was designed and built to cruise at 7.5-8 knots.
Sorry, I digressed. Anyway I want to change out the lubricant. I have read just about everywhere not to use ATF but to use SAE30 or SAE40. THis is okay. But, the filling cover on the right side of engine has ATF embossed on it…. The current lub is also ATF. Now, since this is Thailand and the mechanic is a bit suspect anyway. I would like input here. Does anyone recognize the model of gear?? IF yes, I could get the spec’s.. If not, what is the opinion of people here… Use the SAE or use ATF? And if ATF, what or any specific brand or type.

Thanks in advance…

Topic

[Keith Callaghan]

Tony, Thanks. Your opinion is good enough for me. 15w-40 it is….

[Tony Athens]

SAE 40—-IMO, a bad call.

Tony

[Keith Callaghan]

I understand it is ATF gear but in my neck of the world I cannot find a single ATF blend on approved list and since it was suggested 15w-40 is okay and reduces noise, due to high ambient temp. Year round in Thailand I was wondering if Sae40 would be OK. Since I have 6 liters of it on hand.

[Rob Schepis]

“Per the book” it’s an ATF gear and that’s all I have ever used in it. Others can chime in with direct experience as to substituing with an SAE engine oil..

[Keith Callaghan]

Oops sorry. I meant is the SAE40 a no go even if I am in a warm year round ambient climate. Must be 15w-40 or ATF…

[Keith Callaghan]

Wow!! Thanks guys!! SO is the SAE40W a no go?? I bought it already…. I don’t mind changing to 15W-40. Given the fact I am in Thailand and it is always over 70 degrees F here, please advise.

[Rob Schepis]

Oops, Tony replied before I hit send. See the arrow in this pic – that’s the drop in filter location.

See this prior thread
https://www.sbmar.com/community/topic/newbie-trans-questions/

[Rob Schepis]

?? Sure looks like a ZF to me…

[Tony Athens]

The gear in the PICTURE is made by ZF ( not by Twin Disc).. It’s designed to use a DEXTRON spec ATF, although from past field experiences and a memo from ZF, 15W-40 dieel engine oil can offer better lubrication and noise reduction in many cases…. Probaby a ZF80A..

Tony

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