Transmission fluid

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Scott

Scott

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Sep 24, 1997
242
Hunter 31_83-87 Middle River, Md
Have a Yanmar 2gm20f. When the boat was puchased many years ago, Yanmar speced 30w oil for both the engine and transmission. Several years ago, they changed spec to multi-viscosity oil for engine. Should 30w oil be used in the transmission or is multi-viscosity okay. My gut feeling tells me to stick with 30w. Opinions appreciated. :confused:
 
Tommy T

Tommy T

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Apr 1, 2007
80
Hunter 34 Nashville TN
I don't see where there would be a problem with either oil. Just to be safe stick with the manual.

I have a 3GM30F and the manual for it calls for ATF fluid.
 
kloudie1

kloudie1

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Nov 6, 2006
10,219
Hunter 34 Mandeville Louisiana
Tommy, I am surprised at your engine.. Most 34's had the 3 GMF (some early 34's had a Westerbeke 4 cyl) and the transmission case has a sticker that says 30 wt..
Now Yanmar is specifying "Engine Oil" for our transmissions which means 15-40 is fine. Whatever you are using in your engine, Scott.. which should be a good diesel rated premium (not synthetic) oil.. like Shell Rotella or Mobil Delvac or Chevron's Delo.
 
Tommy T

Tommy T

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Apr 1, 2007
80
Hunter 34 Nashville TN
I have never had to add any oil to the transmission since I have had the boat. The manual said to use ATF in the transmission. Maybe I should research the oil required for that transmission before I need to add any. I have alway heard to use the same oil in the transmission that the engine takes. So I was surprised when the manual stated to use ATF fluid. I need to find out for sure before adding or changing oil in the transmission.
 
rardiH36

rardiH36

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Jun 21, 2007
2,118
Hunter Cherubini 36_80-82 Sausalito / San Francisco Bay
Good chance that name plate on the side of the transmission might also have the oil type specified.
For example here's a picture of the name plate for the transmission on my Yanmar 2QM20.
 

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kloudie1

kloudie1

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Nov 6, 2006
10,219
Hunter 34 Mandeville Louisiana
rardi has it.. look at the hidden side of the transmission on your 34, Tommy.. Mine has a Kanzaki KM3A which calls for "engine oil" .. It will probably say 10-30 wt CC.. on the tag but those specifications have been superseded.. 15-40 CJ-4 is what today's engine oil is..
If you find that the transmission is a KBW10D, that one would require ATF.
ya have to get a light and mirror and scrunch down in that hole under the bunk pad.. Happy Hunting
 
woodster

woodster

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Sep 15, 2009
6,244
S2 9.2a Fairhope Al
Looking from the rear....

.....this is what it looks like on my KM2-C that is mounted to my 2GM20F....

regards

woody
 

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Tommy T

Tommy T

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Apr 1, 2007
80
Hunter 34 Nashville TN
Thanks for the info on the name plate location. They sure don't put them where you can easily view them.
 
B

Benny17441

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May 24, 2004
7,215
CC 30 South Florida
Stick with W30 for the tranny. The oil requirements for the engine and transmission vary. The engine operates in a wide temperatuer range while the transmission does it in a a quite narrow range. In the engine it operates under pressure while in the transmission it is just stirred by the gears. The engine does benefit from a multigrade oil as the oil will adjust to maitain optimum viscocity with increases in temperature. This same oil will not properly adjust viscocity in the transmission. Think of it as making oatmeal which will thicken with heat until it reaches a desired consistency but will remain a watery soup if no heat is applied. It just happens that 30W oil was a fair compromise for use in both engine and transmission so the plates and manuals of the time were somewhat shortsighted in indicating to use the same oil for engine and transmission now that engine oil has evolved to a more specialized fluid. I'm not saying a multigrade cannot be used for the transmission but keep the range narrow; perhaps a 20W40.
 
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