What oil to use?

jwerkjr

jwerkjr

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Mar 24, 2012
63
Hunter 34 531 East Patchogue NY
I am about to change the oil in my 1984 diesel and transmission. The shop manual calls for CB or CC grade 30 or 40 weight with a recommendation of Shell Rotella or Mobil Delvac. With CB and CC being obsolete, I am concerned about what oil to use. I assume that the newer oils would be fine but figured I'd check first. The transmission calls for CC grade 20W30 which I have been unable to locate. Is diesel oil or regular gasoline engine oil used in the transmission? What would be a readily available oil to use, Thank you !
 
Ken13559

Ken13559

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Oct 29, 2005
2,356
Hunter Marine 326 303 Singapore
CD grade should be ok. Some engine maker mention not to use CH-4 grade. I don't know why.
 
Terry Cox

Terry Cox

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Dec 25, 2000
5,731
Hunter Passage 42 Shelter Bay, WA
I have always used Chevron Delo 400 brand engine oil in our boat diesel engines. Our Yanmar engine has a plate on the bell housing that connects the transmission to the engine. This plate states what type of oil the maker recommends for the transmission. Ours states ATF. Some others state engine oil. Worth a check, IMHO.

It would also be helpful to know your engine and transmission brand. Our previous boat, an H28, came with a Yanmar 2GM, which I used Delo 400 in the engine and transmission.
 
B

Benny17441

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May 24, 2004
7,131
CC 30 South Florida
Your shop manual is 30+ years old and in the elapsed time lubricants have changed and significantly improved. Also the wear condition of the engine may favor the use of some grade of oils over others. In your latitude for a healthy engine I would use 15W-40 Shell Rotella. On the transmission 30W oil will be fine.
 
jwerkjr

jwerkjr

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Mar 24, 2012
63
Hunter 34 531 East Patchogue NY
I did check the plate previously to discover the transmission calls for SAE 20/30 HD. It's a Kanzaki KM3-A. I'm just not sure if this means regular automotive oil or diesel oil. (Not sure what the HD stands for). The engine is a Yanmar 3GMF and I did wind up buying the Shell Rotella T1 straight 30 weight because it specified that it was designed for older engines.
 
kloudie1

kloudie1

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Nov 6, 2006
9,892
Hunter 34 Mandeville Louisiana
Rotella or Delo or Delvac are all fine for the Yanmar; the list of API certs should have "CF" on it. The older ones do not want synthetic .. As Benny says, the 15/40 for the engine is perfect but don't go with the syn for the gearbox either, a straight grade oil is best .. like a 30 wt engine oil.. The multigrade oils (15-40) have "viscosity index modifiers" in them which makes them do what they do.. They are best for use in the engine.. The viscosity modifiers are sensitive to being sheared by the gear face contact, which gradually makes the oil go toward its lower viscosity rating.. so a 15/40 in a gearbox after a good bit of use will end up as a 15/20 or a 15/15.. and not so good for the gears. A straight 30 in the box will stay pretty much close to the original 30 with use. Any effect in real world terms? Probably not but that change in vis can be measured in the lab and I am not so keen on doing Kanzaki research ! Recap: multigrade is fine in engine, straight grade in the transmissions that call for motor oil in 'em.
 
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B

Benny17441

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May 24, 2004
7,131
CC 30 South Florida
When they say 20/30 it means that you can use either one single grade. In colder climates the 20W will flow easier. For engines with high hours a thicker oil is beneficial as it helps compression but in the transmission it really does not matter, I would go with a grade suitable with the temperatures the boat is going to be used in. 30W should be fine for temperatures above freezing. Diesel oil is fuel so use motor oil for the transmission.
 
Gunni

Gunni

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Mar 16, 2010
5,937
Beneteau 411 Oceanis Annapolis
Regular single viscosity engine oil. They typically get the HD rating because they reliably stay at the single viscosity. This is interesting because a bunch of us have Kanzaki transmissions that specify automatic transmission oil. In any case I extract and replace every year to make sure the additives stay fresh.
 
kloudie1

kloudie1

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Nov 6, 2006
9,892
Hunter 34 Mandeville Louisiana
The fundamental difference in the transmissions is that the ones that use a friction disk pack clutch specify ATF.. the ones that use a cone clutch specify motor oil..
 
Gunni

Gunni

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Mar 16, 2010
5,937
Beneteau 411 Oceanis Annapolis
kloudie1 said:
The fundamental difference in the transmissions is that the ones that use a friction disk pack clutch specify ATF.. the ones that use a cone clutch specify motor oil..
Click to expand
I believe my Kanzaki KBW 20 is a cone clutch transmission and it runs ATF. My old motorcycles ran wet-clutch (essentially a friction disk clutch) and they used motor oil. For my race bike I found special synthetic oil to provide superior clutch fade performance. I suspect that would also apply to a marine transmission since they are also extreme duty systems.
 
Terry Cox

Terry Cox

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Dec 25, 2000
5,731
Hunter Passage 42 Shelter Bay, WA
The 4JH2-TE Yanmar Owners manual that came with the boat stated to use engine oil in the Kanzaki transmission. That is what the PO used. Later I purchased a 4JH2-TE Yanmar Service Manual and it said to use ATF. Then I discovered the plate on the bell housing and it said to use ATF. So ATF it is.
 
N

newage1461

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Oct 20, 2011
127
Hunter 30 Green Bay
I've used full Syn oil in all my engines for years with no problems at all. Weed eaters, mowers, tractors with gas & diesel and 2 boats with diesel engines.
 
JamesG161

JamesG161

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Feb 14, 2014
7,418
Hunter 430 Waveland, MS
I was curious about diesel engine oils and what was best to use, also...
What the heck was this CC, CD... or CX meaning?
It is Feds regulating Sulfur emissions! At the time of my Engine manufacture it was CD.

Last I looked it was CJ.
The higher the letter the less the sulfur in the lubricating oil.
So "CX" has no meaning in transmission gear oils.

I have switched to blending my own synthetics oils. 5 quarts 5W20 and 1 quart 10W40. This gives me optimum viscosity range for my Gulf Coast climate. I am now in the camp, that synthethics yield lower carbonization of diesel lubricating oils. The synthetic is "spot on" viscosity and normal oils have traces of lower lubricity oils that "seep past" rings and valves to burn.

My Volvo Penta starts faster than my Ford Expedition.:)
Jim...
 
kloudie1

kloudie1

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Nov 6, 2006
9,892
Hunter 34 Mandeville Louisiana
Gunni, the KBW 20 is a multi-disk clutch type transmission hence the ATF.. The higher HP engines as in your boat dictate a smoother clutch than the cone clutches usually can be. Key is to use what the manual for your gearbox says to use.. The old Kanzaki units were in use long before a suitable, readily available "real" gear oil, like what Jim is talking, was available hence the recommendation from Yanmar for a straight grade motor oil for those old units. Remember too that gear oil numbers are different from crankcase oil numbers.. a 30 wt crankcase oil is about equivalent (in viscosity, not additives) to an 80 wt gear oil..
 
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Gunni

Gunni

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Mar 16, 2010
5,937
Beneteau 411 Oceanis Annapolis
Thanks Claude; My Kanzaki Tuff Torq KBW 20-1 plate says "ATF". Talking with the Yanmar folks I was told that the original ATF grade was no longer made and to use Dextron III. So I have been changing out each year with Castrol Transmax ATF - on the basis of all the Japanese autos listed on the bottle! :) I'm a big proponent of frequent auto transmission oil changes. I change the Kanzaki every year when I do my winter layup oil change.
 
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