1983 Yanmar 1GM engine -- Oil for Gear Case

[H216Sailor]

The Yanmar engine manual that I have is written in several languages. Unfortunately, clear English language instructions wasn't a high priority item in writing the manual.

The recommended engine lube oil for the operating temperature range is a 15 w 40. I plan to use the Shell Rotella Oil for the engine. As near I can tell from my very rough interpretation of the German language in the manual, I'm to use the same oil in the gear case as used in the engine.

In reviewing several posts on this web site, it seems that maybe a heavy duty 30 weight oil might be better than the mult-grade engine oil that I plan to use in the engine.

Any guidance on the correct oil for the gear box would be appreciated.

[DrB]

I have the Yanmar 30GM engine in my boat and use Yanmar oil in the tranny and crack case. I figure Yanmar wouldn't make and recommend oil that isn't compatible with their motors. Same price as the other stuff that folks recommend.

If you don't have a Yanmar Service dealer nearby, contact Yanmar directly and see what alternatives they recommend. Why take a chance on random brand oil that is like $6/quart on a motor that is probably around $5000 fully installed.

Drb

[rperret]

my 2004 1GM10 says same oil for engine and the transmission. that said, the engine can use different oil depending upon operating conditions.

www.yanmarhelp.com might help, or marinedieseldirect.com (torrensen marine)

[H216Sailor]

DrB,

Thanks for your reply.

The 1983 Yanmar engine manual list Shell Rotella as a recommended engine oil lube, along with Mobil Delvac and Esso and BP. Apparently in those days, Yanmar did not market an oil as they do now.

The Shell Rotella has basically the same specifications as Yanmar 15 w/40 engine oil (i.e. meets API CI-4, meets or exceeds API CH-4, CG-4, CF-4 and CF/SJ). In fact, I think it cost a bit more than the Yanmar oil. It is not the cost of the Yanmar oil but the availability in our area that is the problem.

Would you happen to know who makes the oil that Yanmar sells?

Being new to diesel engines, I wonder why the gear box needs a multi-grade oil when the temperature of the oil in the gear box is relatively constant. As some of the posts suggest, maybe a high grade 30 weight heavy duty oil may be better for the gear box. However, if that is not the case I have no problem putting the best oil available in the gear box. As you say, the cost of the lube oil is a relatively small matter compared to the cost of a new engine or gear box.

[DrB]

I am not real familiar with the 10GM model, but my 30GM uses the same oil (weight and type) in my tranny and the motor crank case.

I am not sure I agree with you that the tranny is fairly constant in temp. when operating. As you put more load on the engine, I would think the tranny would heat up unless it is actively cooled. Mulitweight oil allows the oil to "flow" in a varity of temperatures, whereas a single weight, works well in a more narrow temperature range. So again, I would check the manual or with a Yanmar dealer before you substitue a single weight oil for a mulitiweight. They may say it is fine, or they may say that the recommend the multiweight. Also, as rperret states, the tranny oil and the engine oil could be different depending on the tranny. Best to check for your specifc tranny.

I don't know who makes the Yanmar Oil, could be anyone. It's good to know that the Rofella is recommended in your motor. If that is easier for you to get, using it shouldn't be an issue. I can easily get the Yanmar stuff, so I do.

Good Luck with it.

DrB

[trantor12020]

I've 2GM20F. Same oil for crankcase and gearbox(KM2P) Mobil Delvac MX 15W40.

[Rockter]

If it says 15W/40 for the motor, then use 15W/40.
In very cold weather, the 30 grade may take too long to get circulated.
We have these oil discussions all the time. Use what's recommended.

[Shortman]

Recommended and use same in tranny as engine. Took the Mack Boring Day With Your Diesel and this is what Larry Berlin recommended. Boat yard questioned because they don't work on many Yanmars, but that's what I have stayed with.
IMHO Shell, Mobil, etc. any well know brand name. Just not Wally World's supreme for $0.65/qt.

[JohnRPollard]

Yes, Same oil in the transmission as in the crankcase for 1GM, 2GM and 3GM.

However, if you are in a temperate climate, the transmission will be fine with a straight 30W oil (properly rated.) I mention this, because the transmission oil usually does not need to be changed as often as the crankcase oil. So if you use 15-40 or 20-50 crankcase oil during your hot season, and change over to a 10-30 during your cold season, you would be probably be fine just going with a straight 30W in your transmission the entire time. The transmission will be warmed somewhat by/during engine warm-up, so it is not as critical to have a multi-weight oil for cold-weather starts.

That said, a 15W-40 works well in both the crankcase and transmission for the temperature ranges in which most of us typically sail.

[H216Sailor]

Thanks to all those providing comments on my question. Everyone had an answer or offered ways to get the correct answers and that is very helpful.

It's obvious there is a lot of experience posting to this site and a willingness to share their knowledge with those needing help.