Yanmar 3GM30 gearbox oil

Kelpie

Kelpie

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Need to top up the gearbox... seems that it needs SAE20-30... I've come across some SAE30 in the shed, but it's for the lawnmower. Any harm in using it? The only info on the bottle is that it is Castrol Garden 4T and it is rated to SAE30 and API SF. Google not being terribly reassuring. I have no wish to do any damage to my gearbox!!
 
The usual guide is that the gearbox uses the same grade of oil as the engine. From memory, that is a fairly basic non synthetic engine oil. In the workshop manual Yanmar specify an oil of grade CC or CD 20W for temps 1-20C, 30 or 40W above that.
 
The grades I have quoted above are those sepcified in the worshop manual for the engine and therefore by default for the gearbox.
 
Kelpie said:
I don't think I fancy using the same oil as the engine, 15w40 can't be the same stuff as SAE20/30...
Click to expand...

The trouble is that the viscosity ranges of multigrade oils has widened over the years, if trouble is the right word.

whereas at one time you'd get a 20W/30 oil meaning that it had the flow characteristics of a grade 20 oil at very low temperatures but the viscosity of a grade 30 oil at 100C. now you find oils have a much wider range and you'll now more likely to find a 15W/40, or even 10W/40, oil meaning it has the flow characteristics at low temperatures of a grade 15, or grade10, oil but is as thick as a grade 40 oil at 100C.

You are not much interested in the W figure as it relates to pumpability and flow at subzero temperatures.

You might find the data in this link useful http://yanmarhelp.com/i_box2.htm
 
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I have used the same oil in the KM3P gearbox as in the engine of my 3GM30F for the last 12 years or so, as stated in the manual. I can still buy API CD with a viscosity of 15w-40, which is what I have always used.
 
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