Transmission oil- can I use mulitgrade?

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Insequent
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Ocean Alexander 50 Mk I
I have Twin Disc 506 trannies. It is recommended to use SAE 30 oil in them, which I've been doing. My usual source for oil only has it in stock occasionally, but I could order it in advance no problem.

However, I'm curious about whether there would be any issues in using a multigrade oil such as 15W-40 or 5W-30. Both of these are readily available.
 
I have twin disc trannies connected to Cat 3208T/A. It calls for 30w oil, but this is NOT motor oil. It is gear oil. Make sure you confirm the proper oil or it will do damage to your trannies. I can give you the CAT part number if you want it.
 
Insequent said:
I have Twin Disc 506 trannies. It is recommended to use SAE 30 oil in them, which I've been doing. My usual source for oil only has it in stock occasionally, but I could order it in advance no problem.

However, I'm curious about whether there would be any issues in using a multigrade oil such as 15W-40 or 5W-30. Both of these are readily available.
Click to expand...

I have mg5061 gear and service manual say: use only SAE-API service class CD engine oil certified to meet TO-2 transmission oil specification or type C-3 transmission fluid. Also approved is SAE-API service class CC engine oil.

Steady operation conditions(GEAR OIL) 150°-185° f SAE30 and 185°-210° f SAE40

And Multi-viccosity oils (i.e. 10W-40, etc.) should not be used in Twin Dick marine Transmissions.

I hope help your oil questions.

NBs
 
Alaskan Sea-Duction said:
I have twin disc trannies connected to Cat 3208T/A. It calls for 30w oil, but this is NOT motor oil. It is gear oil. Make sure you confirm the proper oil or it will do damage to your trannies. I can give you the CAT part number if you want it.
Click to expand...

The gear oils readily available here range from 50W to 90W, definitely not suitable. When the trannies were rebuilt I was advised to use 30W, and that some 30W motor oil I already had was fine. I'll stick with it, and try and check with the local TD dealer.
 
North Baltic sea said:
I have mg5061 gear and service manual say: use only SAE-API service class CD engine oil certified to meet TO-2 transmission oil specification or type C-3 transmission fluid. Also approved is SAE-API service class CC engine oil.

Steady operation conditions(GEAR OIL) 150°-185° f SAE30 and 185°-210° f SAE40

And Multi-viccosity oils (i.e. 10W-40, etc.) should not be used in Twin Dick marine Transmissions.

I hope help your oil questions.

NBs
Click to expand...

Thanks. I'll check into the detailed spec of the 30W engine oil available nearby. And also contact local TD dealer as I noted above.
 
Last edited:
I have a TD 506 also. The qts or litres of HD 30 have almost disappeared so I now go to the local oil distributor a get a 4 jug x 4 litre case of the 30. It will keep.
It helps that my gear system uses about 8 to 9 L to fill the gear, cooler, lines and filter.
 
A TD manual dated 2008 covering a range of trannies states that multi-viscosity oils cannot be used without written permission from TD. So that kinda settles that, even though I have not had a response to me email to TD as yet.

I found a 69 page service manual for the 506 on Boat Diesel. It says use 30W if heat exchange inlet temp is above 85°F, or 20W if below that temp.

In about 10 days I'll be spending some time away from the city, in farming areas. I'm hoping I'll find an oil supplier somewhere that carries 30W in 20 litre drums. Gear capacity is 5 qts, close to 5 litres. I don't believe my hoses/oil cooler holds very much, and I did not try and drain them last time. I don't think I'll do it this time either.
 
Contact a local distributor such as Shell.
 
My Mechanic used a Caterpillar branded 30 wt oil in my twin Disc boxes, I will check the account to confirm when I get back to my boat, The oil was sourced in Brisbane
 
For Borg Warners, if you do use motor oil for the tranny, they do recommend non-detergent, separating it from regular motor oil....

My tranny had probably 5000 hours / 29 years with plain old Rotella 30Wt HD motor oil in it an it was just gone over by professional shop and got a clean bill of health.
 
Your instinct to ask the manufacturer directly I think is wise. I would NOT take anything from a distributor or mechanic as gospel.

For what it's worth, ZF always required straight 30W oil in their gears (the ones that don't use ATF), but maybe a year or two ago published a new oil specification that now allows multi weight oils in most, if not all of the gears that previously required straight 30W. It makes a huge difference in convenience since I can now keep just one type of oil on board for engines and gears.
 
I also use 30 wt Rotella in my transmissions. I get it from Amazon. Not sure if Amazon works down under.
 
With the additives in gear oil one would think gear oil multi-vis or not would be the most appropriate choice.
With the exception of what the manufacturer recommends of course.
 
I think you guys might be able to use my help in marine gear oil matters. I was the Transmission Fluids Engineer for Allison Transmission from 1990 until my retirement in 2009. Upon retiring from Allison Product Engineering, I started a new company and we specialize in oil analysis for all kinds of equipment including marine equipment. I'm still very active in the oil and additives industry and I'm here to help with oil questions in general or transmission fluid question specifically.

Below is my "bio" from a Technical Paper I wrote entitled "What Boat Captains and Marine Surveyors Should Know about Oils and Oil Analysis". The paper carries my company logo so I can't post it here. If you'd like a copy of the paper, just PM me.

My bio:
Tom Johnson holds a Bachelor of Science degree in Mechanical Engineering Technology from Purdue University and has over 30 years of engineering experience. Tom held the position of Transmission Fluids Engineer for Allison Transmission for the last 20 years of his career. Tom retired from GM and Allison Transmission in 2009. While in his former position at GM and Allison Transmission, Tom worked closely with global oil and additive companies and wrote most of Allison’s lubricant specifications. He directed, managed and oversaw the testing and approvals of hundreds of transmission fluid and engine oil
formulations for Allison Transmission. He also served as a key member of GM’s
Automatic Transmission Fluid and Engine Oil Committees. Tom also held a key
position as a member of the SAE Lubricant Review Institute Engine Oil Committee
where he participated on a multi-OEM panel to review and approve engine oils to
US Army specifications. In this capacity, Tom worked closely with the US Army
Tank Automotive Command to review military specification oils for use in US Army tactical and combat wheeled and track laying vehicles.
 
hzjcm8 said:
I think you guys might be able to use my help in marine gear oil matters. I was the Transmission Fluids Engineer for Allison Transmission from 1990 until my retirement in 2009. Upon retiring from Allison Product Engineering, I started a new company and we specialize in oil analysis for all kinds of equipment including marine equipment. I'm still very active in the oil and additives industry and I'm here to help with oil questions in general or transmission fluid question specifically.

Below is my "bio" from a Technical Paper I wrote entitled "What Boat Captains and Marine Surveyors Should Know about Oils and Oil Analysis". The paper carries my company logo so I can't post it here. If you'd like a copy of the paper, just PM me.

My bio:
Tom Johnson holds a Bachelor of Science degree in Mechanical Engineering Technology from Purdue University and has over 30 years of engineering experience. Tom held the position of Transmission Fluids Engineer for Allison Transmission for the last 20 years of his career. Tom retired from GM and Allison Transmission in 2009. While in his former position at GM and Allison Transmission, Tom worked closely with global oil and additive companies and wrote most of Allison’s lubricant specifications. He directed, managed and oversaw the testing and approvals of hundreds of transmission fluid and engine oil
formulations for Allison Transmission. He also served as a key member of GM’s
Automatic Transmission Fluid and Engine Oil Committees. Tom also held a key
position as a member of the SAE Lubricant Review Institute Engine Oil Committee
where he participated on a multi-OEM panel to review and approve engine oils to
US Army specifications. In this capacity, Tom worked closely with the US Army
Tank Automotive Command to review military specification oils for use in US Army tactical and combat wheeled and track laying vehicles.
Click to expand...


Welcome!
 
can you give your boating "opinions" ?
 
Thanks for replies!

Auskiwi - info on the CAT oil would be useful when you can provide it.

Commodave - Amazon started here with much fanfare and nervousness from competitors last Dec. But they have pretty much flopped so far, not much range and no engine/gear oil, prices often not competitive.

I can source some 30W oil, but not sure of spec at this point. One is Castrol 4T, a 30W oil for 4 stroke lawnmowers. Another is Prolube. I have never heard of them but their product would seem to be suitable.
https://prolube.com.au/shop/diesel-engine-oils/monotec-30-sae-30-cd-sf-3/

The major oil suppliers eg Shell don't appear to routinely carry it in outlets, but likely it can be ordered in.
 
My transmissions hold almost a gallon of oil. I ordered waaay to much when I bought the boat so I still have several oil changes worth of 30 wt left. I would recommend that you figure out how much you will need in 2 years and special order it so you will have a supply if you have a problem.
 
I only used SAE 30 in MG5050 as recommended by TwinDisc, but one thought to add that may or may not be relevant. My motorcycle clutch is lubricated by engine oil from a single sump. The oil is specified for motorcycle use because it contains no "slippery" additives that would cause the clutch to slip and eventually destroy it. So, my guess is you might have the same consideration with a boat transmission. Best to stick to the Twindisc recommended oil.
 
hzjcm8 said:
Only on oil recommendations and/or engine/transmission oil analysis.
Click to expand...

two discussions come up for trannies....

oil or ATF....

and only non detergent motor oil or any new oil with detergent and even multi vis....
 
hgjm8,
Do you think using engine lube oil in marine gearbox’s is an appropriate practice?

Lots of additives for engine oil would be not of any benefit or even harmful in a gearbox application. At best additives like what they put in to keep the oil from mixing w fuels is space lost where oil there could definitely help lubricate the gears and bearings. The extreme pressure additives help the gear oil from prematurely breaking down in gear oils but I don’t think they are found in engine lube oil. There again oil could be substituted for additives that are not needed. But then I see gear oils with multi-vis additives.
It seems to me oils should be chosen to best suit the usage. And additive packages are the biggest variable in specific usage.

Also speaking of additives multi-viscosity improvers are added to lube oil to stabilize the oils viscosity. What are they like physically and what percentage of the oil needs to be removed to accomodate them? I heard or read that VI improvers were very small rubber balls. As a powder probably but I’m curious about this.
 
Insequent said:
Tom
Would the Castrol Garden 4T 30W be suitable for my TD 506's? Castrol claim it is suitable for API CD or CF lubrication needs as well, and NBs (post #3) indicated that CD oil is likely to be suitable.
https://www.castrol.com/en_au/australia/products/other-products/garden/garden-4t.html
Click to expand...

Insequent,
Most engine oils will be suitable for use in marine gear transmissions as they are not friction modified so clutches should lockup soundly and without excessive slip or shudder. Automatic Transmission Fluids (ATFs) could also be used and would provide much longer life than engine oils. ATFs are friction modified and tend to smooth out shifts by laying down a very fine layer of friction modifier chemistry on the clutch friction surfaces. Check with the gearbox manufacturer to see if they now recommend ATF formulations. If so, you'd be best off with an Allison approved TES-295 product since it would be stable for many many hours (perhaps years). I wrote the Allison TES-295 specification when I was there.

API CD and CF are quite old categories. API "C" means "Compression Ignition" so these API categories define diesel oil specifications. Passenger car motor oils (PCMOs), on the other hand, will carry an API "S" designation meaning "Spark Ignition". The latest PCMO API Category is "SN". Whereas the latest API HDDO (Heavy Duty Diesel Oil) category is API CK-4. You'll still find plenty of API CJ-4 oils on the market and they will be quite good at providing viscosity and oxidation resistance along with all the other properties formulated into these products (seal compatibility, rust/corrision resistance, etc).

With regard to the "30W" viscosity, that I see being used here, per SAE, "W" means winter. So, it only applies to multi-grade products (SAE 5W-30, SAE 15W-40, etc). If it's a straight weight viscosity grade (30, 40, etc.) you should refer to it as "SAE 30 Grade". That is the proper use of these viscosity terms. You'll find engine oil viscosity specifications in the SAE J300 Standard (link to the SAE J300 table below).

Hope this helps !!! PS: I'm not here to write books; so, please keep it simple and look through my technical paper.

Links:

API CATEGORIES: API | Oil Categories

SAE J300 STANDARD: SAE J300 | Widman International
 
Nomad Willy said:
hgjm8,
Do you think using engine lube oil in marine gearbox’s is an appropriate practice?

Lots of additives for engine oil would be not of any benefit or even harmful in a gearbox application. At best additives like what they put in to keep the oil from mixing w fuels is space lost where oil there could definitely help lubricate the gears and bearings. The extreme pressure additives help the gear oil from prematurely breaking down in gear oils but I don’t think they are found in engine lube oil. There again oil could be substituted for additives that are not needed. But then I see gear oils with multi-vis additives.
It seems to me oils should be chosen to best suit the usage. And additive packages are the biggest variable in specific usage.

Also speaking of additives multi-viscosity improvers are added to lube oil to stabilize the oils viscosity. What are they like physically and what percentage of the oil needs to be removed to accomodate them? I heard or read that VI improvers were very small rubber balls. As a powder probably but I’m curious about this.
Click to expand...

Nomad Willy,
I discuss "Viscosity Index Improvers" (VII) in my technical paper. Basically, they are very long chain polymers that impart higher viscosity to low viscosity base oils. Take a multi-grade oil like SAE 5W-30. You start with base oils that meet the SAE J300 Standard for SAE 5W oils. Then you add VII polymers that swell with temperature and make the oil act like an SAE 30 grade oil at operating temperature as measured at 100C (212F). With time, these polymers get cut-up by gears and bearings under very high stresses. This action is called "sheardown". It happens with multi-grade oils only and not with straight weight oils. However, you'll have better overall viscosity coverage with a multi-grade oil if the engine is exposed to wide ambient (outside air) temperature swings. I cover this in my Technical Paper.

NOTE: Among other oil parameters, oil analysis, measures the oil's viscosity at 100C. This allows the boat owner to know the amount of shear that has occurred over time and whether or not the oil remains "in grade". For instance, SAE J300 defines oil viscosities and specifies a minimum viscosity of 9.3 cSt (centi-Stokes), as measured at 100C, for SAE 30 grade oils. Once the oil drops below 9.3 cSt, it is no longer considered an SAE 30 oil and may begin to effect engine/gearbox wear since it may no longer be able to adequately support the loads within the engine/transmission (gearbox) gears and bearings.

Hope this helps !!!
 
Last edited:
hgjm8,
I read that to be saying engine lube oil and returns to a viscosity closer to it’s base. In your example 5W-30 would become perhaps 0W-20 after a peroid of time. Is that period of time within normal change intervals or beyond it?

How much “sheardown” does SAE 30 experience? I would expect none as there’s no “polymers” to break down.

I’m one to tend toward using SAE 30 and warming my boat engine up slowly eliminating the need for MV oils. Our engine compartments are kept above 40 degrees with heaters in winter and warm (relative) surrounding waters in contact with the hull. Even in Alaska I had no starting problems whatsoever. I reason my SAE 30 is slightly better at 100c than SAE 5W-30. Any truth in that in your opinion?

Also will an SAE 30 oil have additives that make it more suitable to boats in marine use than SAE 5W-30? My thinking is that SAE W15-40 is best suited as a truck engine lube oil and SAE 30 is more suitable bor boats and marine.
 
Insequent said:
Thanks for replies!

Auskiwi - info on the CAT oil would be useful when you can provide it.

Commodave - Amazon started here with much fanfare and nervousness from competitors last Dec. But they have pretty much flopped so far, not much range and no engine/gear oil, prices often not competitive.

I can source some 30W oil, but not sure of spec at this point. One is Castrol 4T, a 30W oil for 4 stroke lawnmowers. Another is Prolube. I have never heard of them but their product would seem to be suitable.
https://prolube.com.au/shop/diesel-engine-oils/monotec-30-sae-30-cd-sf-3/

The major oil suppliers eg Shell don't appear to routinely carry it in outlets, but likely it can be ordered in.
Click to expand...

Here is what Twin Disc recommended that I use in my Trannies. They told me NOT to use regular automotive 30wt. I have 3208T/As connected to them.
 

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hzjcm8 said:
Insequent,
Most engine oils will be suitable for use in marine gear transmissions as they are not friction modified so clutches should lockup soundly and without excessive slip or shudder. Automatic Transmission Fluids (ATFs) could also be used and would provide much longer life than engine oils. ATFs are friction modified and tend to smooth out shifts by laying down a very fine layer of friction modifier chemistry on the clutch friction surfaces. Check with the gearbox manufacturer to see if they now recommend ATF formulations. If so, you'd be best off with an Allison approved TES-295 product since it would be stable for many many hours (perhaps years). I wrote the Allison TES-295 specification when I was there.

API CD and CF are quite old categories. API "C" means "Compression Ignition" so these API categories define diesel oil specifications. Passenger car motor oils (PCMOs), on the other hand, will carry an API "S" designation meaning "Spark Ignition". The latest PCMO API Category is "SN". Whereas the latest API HDDO (Heavy Duty Diesel Oil) category is API CK-4. You'll still find plenty of API CJ-4 oils on the market and they will be quite good at providing viscosity and oxidation resistance along with all the other properties formulated into these products (seal compatibility, rust/corrision resistance, etc).

With regard to the "30W" viscosity, that I see being used here, per SAE, "W" means winter. So, it only applies to multi-grade products (SAE 5W-30, SAE 15W-40, etc). If it's a straight weight viscosity grade (30, 40, etc.) you should refer to it as "SAE 30 Grade". That is the proper use of these viscosity terms. You'll find engine oil viscosity specifications in the SAE J300 Standard (link to the SAE J300 table below).

Hope this helps !!! PS: I'm not here to write books; so, please keep it simple and look through my technical paper.

Links:

API CATEGORIES: API | Oil Categories

SAE J300 STANDARD: SAE J300 | Widman International
Click to expand...

Thanks for your response! It clarifies things for me.
 
Last edited:
Alaskan Sea-Duction said:
Here is what Twin Disc recommended that I use in my Trannies. They told me NOT to use regular automotive 30wt. I have 3208T/As connected to them.
Click to expand...

Thanks ASD
Your gears are likely more modern than mine, which are 1981. I will try and get a response from the local TD guys that is specific to old 506's. I'm sure the CAT oil would be very good, but I might not need that good a spec.
 
I seem to remember when frequenting automotive workshops that gearbox oils had a distinctive smell. Or was it diff oils? Or both? That said, better rely on manufacturer advice than olfactory senses.
 
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