Gearbox oil?

[Robin]

This link is very helpful, also the associated other pageshttp://www.yanmarhelp.com/i_box2.htm

 

[pathfinderstu]

This link is very helpful, also the associated other pageshttp://www.yanmarhelp.com/i_box2.htm

Thanks for taking the time to post that..very useful I will keep the link for future reference ..using engine oil as stated there has been mentioned and sounds fine however it is the fourth published version of the type of oil to use. which surprises me.

 

[Robin]

Thanks for taking the time to post that..very useful I will keep the link for future reference ..using engine oil as stated there has been mentioned and sounds fine however it is the fourth published version of the type of oil to use. which surprises me.

]

De nada. I was looking for myself to find what oil to use in my own Yanmar 3GM30F gearbox, our service engineer said it should be a HD straight 30 grade engine oil, and the yanmar site agrees but others had told me to use ATF which is what the gearbox on my last uk boat took with a Yanmar 4JHE engine but maybe it had a hurth gearbox. THE manual for my 3GM30 engine, that I found on line says use the same oil as you would use in the engine, which in my case now is Rotella 15-40 IIRC but our engineer used a straight 30 grade in the gearbox ( and said there was definitely not ATF in it before because ATF is pink and distinctive and he left me a container of 30 grade engine oil for top ups so that should do nicely. It should not be this confusing for engines that are this common.

 

[Spi D]

I never knew there was so much to a can of oil!

Although it would make things easier if oil was just oil, it really is not so. Products develop, processing gets refined and requirements change along with technology.

Gear oil is motor oil specifically made for standard transmissions, transfer cases, and differentials in automobiles, trucks, and other machinery. It is of a higher viscosity to better protect the gears. The high viscosity or thickness ensures transfer of the lubricant throughout the gear train.

Automatic transmissions use automatic transmission fluid. Manual transmissions use a variety of oils: Regular motor oil, heavyweight gear oil, or even automatic transmission fluid in some rare cases.

Any specific info given from manufacturers of course overrule such general guidelines.

Sorry for he lenght of this - suggest you get a coffee and read on

Gear Oil Basics
High quality gear oils must lubricate, cool and protect geared systems. They must also carry damaging wear debris away from contact zones and muffle the sound of gear operation. Commonly used in differential gears and standard transmission applications in commercial and passenger vehicles, as well as a variety of industrial machinery, gear oils must offer extreme temperature and pressure protection in order to prevent wear, pitting, spalling, scoring, scuffing and other types of damage that result in equipment failure and downtime. Protection against oxidation, thermal degradation, rust, copper corrosion and foaming is also important.

Gear Oil and Motor Oil Are Not the Same
Gear oil differs from motor oil. Most people assume that SAE 90 gear oil is much thicker than SAE 40 or 50 motor oil. However, they are the same viscosity. According to AMSOIL Technical Drivetrain Products Manager Kevin Dinwiddie, the difference is in the additives. “Motor oil has to combat byproduct chemicals from gasoline or diesel ignition and should contain additives such as detergents and dispersants,” said Dinwiddie. “Since an internal combustion engine has an oil pump and lubricates the bearings with a hydrodynamic film, the need for extreme pressure additives such as those used in gear oils does not exist in engines.” Engine oils and gear oils both have anti-wear additives, and they both must lubricate, cool and protect components, but gear oils are placed under extreme amounts of pressure, creating a propensity for boundary lubrication, a condition in which a full fluid lubricating film is not present between two rubbing surfaces. For example, differentials in cars and trucks have a ring and pinion hypoid gear set. A hypoid gear set can experience boundary lubrication, pressures and sliding action that can wipe most of the lubricant off the gears. To combat this extreme environment, extreme pressure additives are incorporated into the oil. AMSOIL uses an extra treatment of extreme pressure additives in its gear oils in order to reduce wear and extend the gear and bearing life.

Additional Differences
Because many of the components found in the drivetrain consist of ferrous material, the lubricant is required to prevent rust and possible corrosion to other materials. Rust and corrosion problems are not nearly as prevalent in engines. The many small and intricate components that make up gear sets found in the drivetrain can be quite noisy and may be subjected to shock loading. The viscosity and extreme pressure formulation of gear oil quiets gears and dissipates shock loading. The rotating motion of the gear sets also tends to churn the lubricant, resulting in foaming. If a gear lube foams, the load carrying capacity is significantly reduced because the air suspended within the oil is compressible. For example, when the gear teeth come into contact with each other any trapped air bubbles will compress, therefore reducing the thickness of the separating oil film. In turn, this reduction could lead to direct metal-to-metal contact between gear teeth and result in accelerated wear. The gear oil must have the ability to dissipate this entrapped air, insuring a sufficient lubricating film exists to protect the gears from contact wear.

Typical Drivetrain Fluid Additives
Much like engine oil, the chemical compounds, or additives, added to drivetrain base stocks either enhance existing properties or impart new ones. Some of the additives that may be found in a drivetrain fluid include the following:

- Extreme pressure and/or antiwear agents - These additives are used to minimize component wear in boundary lubrication situations.
- Pour point depressants - This type of additive is used to improve low temperature performance.
- Rust and corrosion inhibitors - These are used to protect internal components.
- Oxidation inhibitors - These additives are used to reduce the deteriorating effects of heat on the lubricant, increasing the lubricant’s service life.
- Viscosity index improvers - These allow a lubricant to operate over a broader temperature range.
- Anti-foam agents - These are used to suppress the foaming tendency and dissipate entrapped air.
- Friction modifiers - The required degree of friction reduction can vary significantly between differing pieces of equipment in drivetrain applications. In some cases, friction modifiers may be required to obtain the desired results.

Gear Design Dictates Lube
Design Gear designs vary depending on the requirements for rotation speed, degree of gear reduction and torque loading. Transmissions commonly use spur gears, while hypoid gear designs are usually employed as the main gearing in differentials. Common gear types include the following: Maintaining a vehicle requires the use of many lubricants, each specifically designed to perform a certain task or set of tasks. The most common lubricant requiring routine attention from motorists is engine oil. Gear oil, on the other hand, is oftentimes overlooked when it comes to scheduled maintenance. gaging the gears, as is required in a manual transmission. Instead, clutches and bands are used to either hold or release different members of the gear set to get the proper direction of rotation and/or gear ratio.

Spur
Spur (straight cut) gears are widely used in parallel shaft applications, such as transmissions, due to their low cost and high efficiency. The design allows the entire gear tooth to make contact with the tooth face at the same instant. As a result, this type of gearing tends to be subjected to high shock loading and uneven motion. Design limitations include excessive noise and a significant amount of backlash during high-speed operation.

Bevel
Bevel gears (straight and spiral cut) transmit motion between shafts that are at an angle to each other. Primarily found in various types of industrial equipment, as well as some automotive applications (differentials), they offer efficient operation and are easy to manufacture. As with spur gears, they are limited due to their noisy operation at high speeds and are not the top choice where load carrying capacity is a requirement.

Worm
Worm gear sets employ a specially-machined “worm” that conforms to the arc of the driven gear. This type of design increases torque throughput, improves accuracy and extends operating life. Primarily used to transmit power through non-intersecting shafts, this style of gear is frequently found in gear reduction boxes as it offers quiet operation and high ratios (as high as 100:1). Downfalls with this type of gear set are its efficiency, high price per HP and low ratios (5:1 minimum).

Hypoid
Hypoid gear sets are a form of bevel gear, but offer improved efficiency and higher ratios over traditional straight bevel gears. Commonly found in axle differentials, hypoid gears are used to transmit power from the driveline to the axle shafts.

Planetary
Planetary gear sets, such as those found in automatic transmissions, provide the different gear ratios needed to propel a vehicle in the desired direction at the correct speed. Gear teeth remain in constant mesh, which allows gear changes to be made without engaging or disengaging the gears, as is required in a manual
transmission. Instead, clutches and bands are used to either hold or release different members of the gear set to get the proper direction of rotation and/or gear ratio.

Helical
Helical gears differ from spur gears in that their teeth are not parallel to the shaft axis; they are cut in a helix or angle around the gear axis. During rotation, parts of several teeth may be in mesh at the same time, which reduces some of the loading characteristics of the standard spur gear. However, this style of gearing can produce thrust forces parallel to the axis of the gear shaft. To minimize the effects, two helical gears with teeth opposite each other are utilized, which helps to cancel the thrust out during operation.

Herringbone
Herringbone gears are an improvement over the double helical gear design. Both right and left hand cuts are used on the same gear blank, which cancels out any thrust forces. Herringbone gears are capable of transmitting large amounts of horsepower and are frequently used in power transmission systems.

The differences in gear design create the need for significantly different lubrication designs. For instance, hypoid gears normally seen in automotive differentials require GL-5 concentration and performance of extreme pressure additives. “This is because of the spiral sliding action that hypoid gears have,” said Dinwiddie. In differential applications that utilize hypoid gears, AMSOIL typically recommends one of the following: SEVERE GEAR Synthetic Extreme Pressure 75W-90 (SVG), SEVERE GEAR Synthetic Extreme Pressure 75W- 140 (SVO), SAE 80W-90 Synthetic Gear Lube (AGL), Long Life Synthetic Gear Lube SAE 75W-90 (FGR) or Long Life Synthetic Gear Lube SAE 80W-140 (FGO) Most manual transmissions have helical gears and do not require GL-5 performance. “The helical gear is almost a straight cut gear, but on an angle,” said Dinwiddie. “There is spiral action and very little sliding action, hence there is less need for extreme pressure additives.” GL-4 gear lubes have half the extreme pressure additives of GL-5 lubes. In manual transmissions utlizing helical gears, AMSOIL typically recommends one of the following: Synthetic Manual Synchromesh Transmission Fluid (MTF) or Synthetic Manual Transmission and Transaxle Gear Lube (MTG). AMSOIL Provides Gear Oil Options AMSOIL carries drivetrain lubricants to meet nearly every application. The synthetic base stocks and top-quality additive packages found in AMSOIL gear lubes and transmission fluids provide the ultimate in wear protection for cars, trucks, outboards, heavy-duty and racing applications.

 

[Robin]

all the information in the last post is very informative (thanks for posting it) about the mechanics and the lubricants, but like most folk I'm just a mere yottie who needs a simple answer as to what oils to put in my boat engine and it's transmission when it is being serviced or topped up in operation.

 

[dial-a-monkey]

I'm also looking to change the transmission oil but the only oil available here in Panama is SAE 40 HD, perhaps due to the ambient temps of > 30 degC?

Anyone willing to wager an opinion if this 40# weight HD oil would be suitable? as mentioned in this thread the recommendation for my Kanzaki KM35P is for mono grade 20# or 30# HD.
I'm hedging that if using 15W40 motor oil is OK then SAE 40 should also be OK. I also have hydraulic oil at SAE 32!!

Thanks.

 

[BelleSerene]

I have the same engine/gearbox and I'm pretty sure it's a monograde oil needed, either SAE 20 HD or SAE 30 HD.
I use SAE 30 HD (Heavy Duty) engine oil.

I too have the same KM35P gearbox, and the recommended oil is also stamped on the plate at the aft end - 0.5l of 'SAE 20/30 HD'. I too was told that the HD was important (I read it's about a detergent additive to cope with high wear but I don't pretend to understand the mechanics or the chemistry of it) and that it indicates a choice between 20 & 30. I'm using SAE 30 HD oil in it. I know just because I had to replace the oil last month when we took the box out to fix a clutch problem.

 

[charles_reed]

I have this engine and am pretty certain it has the same gearbox (Number rings a bell but service manual files are about 12,000+ miles away). My wife's godson is a Yanmar dealer and he told me to use the normal engine oil in the gearbox. I also checked the operation & service manuals and found the same information in one of them. I can check but won't be back in UK for a couple of weeks (don't think I've put those docs. into Cloud based storage yet).

This is what I've always done with the two Yanmar engines I've had. Here in Greece I've found that most Shell garages also stock a range of "Coral" products, one of which is the very SAE 30 oil for diesels for which you're looking.

 

[charles_reed]

Rather than attach SpiD's prolix obfuscation - the Yanmar gearbox which is being discussed is a simple double-cone-clutch one and in fact Hypoid-type oils would probably result in the cones starting to slip.
Most marine engines and Yanmars especially are produced for mass markets in 3rd world countries - modern high-performance oils are wasted on them and can genuinely cause problems (valve guide seal wear) with high-detergent oils.
So the cheaper the better....
Just change it frequently.

 

[lpdsn]

I've a 4JH 2BE engine. I managed to download a manual from a German website a few years ago. If I try clicking on a link I'm directed to www.sagaforumet.com (sounds Swedish) but I haven't actually allowed my browser to go to that link so can't verify it - I definitely got it from a .de site.

It says it covers 4JH (B)E so probably covers the OPs.

There are two Gearbox chapters. One for Kanzaki-Carl Hurth KBW 20 & 21 and one for KM4A. The first chapter specifies Dexron and several equivalents (the second doesn't mention anything). From the age of the gearbox I guessed Dexron II. I bought an equivalent from Amazon (brand = Comma), which wasn't expensive (just under £20 incl delivery to Ireland - think I bought a couple of paperback too to get the delivery cost down).

This is not the same gearbox as yours I believe, but sounds similar. Would be worth looking for a manual that covers yours.