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Discussion Starter #1
Dumb question but how often should you change the transmission oil?

I have a 83' 32 Morgan with a 23hp Yanmar 3GMD. I bough the boat last year and the previous owner took very good care and I would like to do the same. I change the engine oil twice a season but never really think about the tranny oil.

Also what type of oil or fluid would I use? Is there any other preventative maintenance I need to do on the tranny besides lubing and checking the cables?
Thanks
 

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best bet is not to assume you have the correct or original tranny, whatever that was, and to see what tranny you have. Then find out what oil it needs.

The spec has probably changed since 1983, don't be surprised if the original fluid is obsolete and there's some new replacement for it.
 

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Discussion Starter #4
Do different manufacturers take different types of oil? Also this is really dumb but is there oil and fluid or is it the same thing. Also where would you purchase this? West Marine? Thx
 

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It depends on

It all depends on your tranny. Most Hurth/ZF boxes take ATF and many of the Kanzaki transmissions on Yanmars take ATF as well but then some take regular motor oil.

You need to ascertain the correct fluid for your particulr transmission on an individual basis.
 

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Discussion Starter #7
Ok quick revival of this. Found out the transmission I have is a Yanmar KM3A and the manual I found says to put same oil as engine. I am using Rotella T 15w-40. Is this ok or should I go with 30w?
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Does your manual say to use straight 30 oil in the engine? Or that a range of mutli-vis oils are OK by temperature?

AFAIK transmissions that use engine oil usually use the straight 30, not the multi-vis, but Yanmar might be more liberal. Why not ask them directly to be sure?
 

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KM3A transmission

You may find that the manual and the workshop manual are conflicting one calls for automatic tranny fluid and the other regular engine oil for the KM3A transmission.

The requirement is for 20 or 30 weight motor oil not multi-weight (ie. 5w30) and not synthetic oil

You will find this info on the identifier plate on the top of the gearbox of the transmission, I suggest that you believe this before any dealer's advice or any printed material.
Assume that since it is carved in steel and an attached part of the transmission case, it is as good as "carved in stone"

With normal use you should change the oil annually as the manual suggests, It should take .3 of a litre, don;t overfill, check levels with the dipstick not screwed in but just sitting on the top of the hole unlike the way that engine oil is checked ( with the dipstick pushed all of the way in)
 

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The cone in the transmissions are costly to replace. Make double sure your linkage is adjusted to manufactures specs. including the spring joint (very important)The spring joint if properly adjusted holds pressure on the transmission shift lever in both forward and reverse. Once the cone is engaged you don't want it to slip. It was recommended to me to NOT use muti grade oil or oil with detergent it's just to slick. I use non detergent 30 weight and change it every 150 hrs or every other engine change.

 

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For what it's worth. My boat has a Volvo-Penta set-up and I use Rotella T 15-40 for the engine and Rotella T 30W for the transmission. BTW, the PO worked for Shell and was one of the developers of Rotella T, he swears it's the best product on the market. I wouldn't dare use anything else now, would I.

Regards...MGM
 

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Hello,

IMHO, transmission oil should be changed based on hours of use, not just time. Unlike engine oil, trans oil is not subject to combustion and all the evils associated with that (soot, high temperature, shear forces, etc.). If you run your engine 200 hours a year, then maybe you should change the trans fluid yearly. However, if you only do 50 hours a year of motoring, changing the trans oil yearly would be way overkill. I would not let the same oil sit in the box for 10 years, but would change it at least every 5 years. For me personally, I usually motor between 50 and 100 hours a year and I will change the trans oil after 200 hours of use.

Barry
 

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Discussion Starter #14
Thanks Barry - By the way when are you putting your boat in? Just got mine in today.
 

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Boat Launch

Thanks Barry - By the way when are you putting your boat in? Just got mine in today.
Hi Nick,

I should be in about two weeks. The weather has been cold and damp, so I don't feel like I'm missing much. I don't have to do too much this year, just scrub and paint the bottom, install a new raw water impeller, fresh bird spikes on the spreaders, and wash the topsides.

Barry
 
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