Which gearbox oil?

Probably not. You will be able to find SAE 30 in places which specialise in more basic/older engines such as agricultural suppliers, chandleries catering for canal craft, or online of course.
One thought, how often do you change the gearbox oil in your car...... Never ! I thought so, me too. Nor have I ever changed it in my boat engine, which does far fewer hours
 
The manual for my 4JHBE specifies Dextron II equivalent for the gearbox. I found Amazon was a good source.

Surprisingly, it also says change every 100 hours, which I've now started to do, but didn't used to and I doubt previous owners did.

If you've got the manual that should really say.
 
Rafiki: I have rarely changed it but am feeling guilty.
lpdsn: Yes I have the manual but for a 2GM20! Yes it says SAE 30, No it does not say don't use 5W30. hence my question.
 
hopefully this helps

5w-30 grade defines the viscosity at 0 o/C (5W) and at 100 o/C (30W).
SAE30 defines the viscosity at 100 o/C .At low temperatures, it will be much thicker which is what you want in a high pressure situations within a gearbox, unlike a 5W-30 in an engine where you want to reduce the cranking effort when the engine is cold. In them there old days, people used to put paraffin heaters under the car's oil pan in the winter to help start the car in the morning. I wonder if that is why we have fire and theft insurance?

tross
 
richardabeattie said:
Rafiki: I have rarely changed it but am feeling guilty.
lpdsn: Yes I have the manual but for a 2GM20! Yes it says SAE 30, No it does not say don't use 5W30. hence my question.
Click to expand...

At lower temperatures 5W30 is "thinner" - lower viscosity - than straight SAE30. That's good for starting an engine from cold, not so good for a gearbox. I'd use 30, If that's what the manual says.
 
It is my personal view that low viscosity oils such as 5w-30 are fine in engines built for them, with hardened steel shafts, but not for more traditional ones with unhardened ones. Gearboxes typically require a little more boundary lubrication than engines do, and in many cases oils like Dextron, which are rich in additives, are required. The smaller Yanmar gearboxes take engine oil, which although specified as SAE 30, has now generally been superseded by 15w-40 to API CF-4.

There is a page on engine oils on my website, which although it does not address gear oils, will give you some background info.
 
Interestingly the manual for my Volvo D2-40 ( basically the current model of Volvo 4 cylinder 1.5 litre engine) used to require a particular Gearbox oil, later versions of the manual ( printed from the Volvo website) say use 15/40 engine oil. The manual does not refer to using this only on engines with a serial number later than xxx. I was told by an engineer that you can therefore use either, but dont mix them.
 
richardabeattie said:
Vyv - are you saying that I can use 15w/40 in the Yanmar sump and also in the gear box?
Click to expand...

There is a lot of confusion in Yanmar publications. The workshop manual for my 3GM30F (which also covers the 2GM20) says use API CC, SAE 10w-30 in the gearbox and SAE 20, 30 or 40 in the engine, dependent upon temperature. The operators' manual says API CE/CD SAE 15w-40 in the engine and gearbox. I do use API CD, which is available in Europe but rarely in UK. I don't think I have ever seen API CE. API CF-4 is a reasonable substitute, viscosity 15w-40.
 
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