Cause Google did not seem to know anything about this topic, I am tossing it to the hive.
Who knows anything about oil changes on ocean freighters? How often do they change oil? How much oil does it require? What kind of oil do they require? The vessels that brought this question up was container ships.
Pete
Come on, y'all... it's been three minutes and there aren't already 5 correct answers?
We're slipping.
I'll give a wrong answer. They're 2-stroke and lubed by the fuel oil.
I know on large diesels in offshore supply boats some of them blend oil in with the fuel and replace it while sending in periodic oil samples. Some send samples and change filters. Some use centrifuges and send samples. If they loose a cylinder or something they get all the shrapnel they can out and go on. New oil at overhaul.
These are HUGE low speed engines.
https://www.reddit.com/r/MachinePorn/comments/1cfiii/the_open_crankcase_and_crankshaft_of_a/?rdt=57952
"Depending upon the bore size, ball park figure would be between 60 - 90 tonnes of oil."
"The crosshead diesel engines, up to 107,000 hp--the ones with the piston rod bolted hard to the piston, then the "wrist pin" like crosshead in the crank case and a connecting rod from there to the crankshaft use two engine oils. The 30 wt. crankcase oil is good for the life of the engine. It has a low TBN because it does not get exposure to the blowby products of combustion--it is more like a "machinery oil" than like an "engine oil". There is a 50 wt or 60 wt cylinder oil that is pumped into ports in the cylinder to lubricate the liner, piston rings, and piston skirt--the larger engines will consume a ton a day. It will be TBN 70 or so for the very high sulfur bunker fuel oil. A lower TBN oil must be used when low sulfur fuel is used. Trunk piston engines, the medium speed engines used for generators or for the diesel electric propulsion systems up to 23,000 hp, will use a 40 wt. oil of 30 to 50 TBN. These also burn the heavy fuel oil. The prices of these oils are often confidential between the suppliers and the ship owners. Suppliers want a long term contract for the entire fleet. And, they are usually bought in bulk by the ton and delivered by tanker truck or barge. The ExxonMobil link above is very informative."
"The crosshead diesel engines, up to 107,000 hp
I know I'm not the only person that instantly starred to wonder what applications this could be used for.
There's a good chance that while deep at sea, the fuel used is much dirtier than the lubrication oil. Can't do that near shore, though- clean fuel instead of bunker fuel.
Total Base Number (TBN) is a measurement of the reserve alkalinity in an engine oil. It quantifies the oil's ability to neutralize acidic compounds, primarily formed from the combustion of fuel. These acidic byproducts can cause corrosion and wear on engine components if left uncontrolled.
The above is a term I had never heard.
Below is another thing I knew nothing about: Crosshead engine design.
Raises hand! (Lapsed marine engineer) When I got my license the world still loved steam ships and large diesels were just beginning to become the norm. My experience was all on steam ships but I've got the books down in my office so I can go see what I can find if needed / requested / challenged? License said " steam and motor vessels of any horsepower" which was kind of cool.
From memory, a large direct reversing propulsion diesel would use hundreds if not thousands of gallons of lubrication oil. There would be centrifugal oil purifiers and filtration systems as well as oil coolers. There would also be a make up lube oil tank for replenishing any oil used by the engine. Most of the slow speed direct reversing engines of my "day" were of a 2 stroke design, the big player at that time (early 80's) was Wartsila. The engines were air started and directly connected to the propeller shaft. Want to stop? Shut the engine off. Want to back down? Start the engine in reverse. Unlike small gas 2 strokes the whole lubrication system was separate and a conventional pressure lubrication system.
Edited to add: I'm also remembering Sulzer as being a big player in the 2 stroke / direct reversing engine manufacturers.
Curtis73 (Forum Supporter) said:Come on, y'all... it's been three minutes and there aren't already 5 correct answers?
We're slipping.
I'll give a wrong answer. They're 2-stroke and lubed by the fuel oil.
Sorry I was watching videos of Ardun heads and superchargers on old Ford flatheads...
They do not do oil changes unless something goes terribly wrong. They do constant lube oil purification though. They are continuously cleaning their oil.
In reply to NOHOME :
When I look at the cross head design it seems effectively just like a really tall piston and skirt.
11GTCS said:Curtis73 (Forum Supporter) said:Come on, y'all... it's been three minutes and there aren't already 5 correct answers?
We're slipping.
I'll give a wrong answer. They're 2-stroke and lubed by the fuel oil.
Sorry I was watching videos of Ardun heads and superchargers on old Ford flatheads...
Acceptable excuse, but now that you Ardun don't let it happen again.
Looks like over 4000 hours for a big cruise ship with the right maintenance schedule:
"To stabilise the oil’s TBN in the Princess Cruises vessels, ExxonMobil recommended an increase in artificial oil consumption of 76 litres a day above current natural consumption.
Without these additions, the oil’s TBN would have reached an excessive level after approximately 4,000 hours, requiring a full sump change. Using artificial, consumption to stabilise the TBN of Mobilgard™ M50 on each of its seven ships, Princess Cruises was able to extend the oil change interval, with overall volume savings of over 81,000 litres in the first year. This equated to significant financial savings, with total lubrication costs falling by more than $100,000."
In reply to ProDarwin :
Given that the bore and stroke on these engines is measured in meters there's a pretty significant side thrust component that needs to be considered. They're somewhat similar in that way to old school reciprocating steam engines which is whole other rabbit hole we could jump down. Full ahead RPM on one of these engines would be about 130 RPM from what I'm remembering if that helps illustrate.
In reply to STM317 :
Cruise ships are a different animal from large container or tank vessels. They typically have multiple medium speed (800 ish RPM) engines driving generators and electric propulsion motors in external pods. (Up to 12 engines / generators and 4 propulsion pods) That way the engines can serve both the large hotel loads of a cruise ship in port and if underway simply run more engines to support the propulsion load. It also adds some redundancy if theres a mechanical or electrical fault with one of the units.
Curtis73 (Forum Supporter) said:Come on, y'all... it's been three minutes and there aren't already 5 correct answers?
We're slipping.
I'll give a wrong answer. They're 2-stroke and lubed by the fuel oil.
Turns out this was the right answer?
RonnieFnD said:"The crosshead diesel engines, up to 107,000 hp
I know I'm not the only person that instantly starred to wonder what applications this could be used for.
Miata.
I know we only changed the oil on our steam turbines maybe once every 5 years? TEP 2190. I don't remember the exact interval but it was very infrequent.
We were also constantly cooling and purifying oil. We used Sharpels or DeLaval purifiers, don't remember which. Both are centrifugal. Cooling was via seawater heat exchangers.
11GTCS said:In reply to STM317 :
Cruise ships are a different animal from large container or tank vessels. They typically have multiple medium speed (800 ish RPM) engines driving generators and electric propulsion motors in external pods. (Up to 12 engines / generators and 4 propulsion pods) That way the engines can serve both the large hotel loads of a cruise ship in port and if underway simply run more engines to support the propulsion load. It also adds some redundancy if theres a mechanical or electrical fault with one of the units.
The Exxon article linked mentions the specific application for a Wartsila 46 series engine. The smallest of which is 8.5 m in length, weighs 97 tonnes, and is rated at 7.2MW of power. The largest being 12.7m long, weighing 233 tonnes and creating 19.2 MW.
Not sure how those relate to cargo ships or military vessels, but they're significantly large engines used in some pretty hefty watercraft.
Curtis73 (Forum Supporter) said:RonnieFnD said:"The crosshead diesel engines, up to 107,000 hp
I know I'm not the only person that instantly starred to wonder what applications this could be used for.
Miata.
Yer gonna need a bigger car... Person for scale.
Turbo_Rev said:I know we only changed the oil on our steam turbines maybe once every 5 years? TEP 2190. I don't remember the exact interval but it was very infrequent.
We were also constantly cooling and purifying oil. We used Sharpels or DeLaval purifiers, don't remember which. Both are centrifugal. Cooling was via seawater heat exchangers.
Geared steam turbines wouldn't have anywhere near the contamination that a propulsion diesel would and what you're stating is exactly what I remember from the steam ships I was on.
Side note, my son is an Aggie (MS in '21) and y'all are currently borrowing the former MMA training ship until the new ships are ready. Gig em, horns down, etc.! I thought MMA was a cult until I took a walk around the campus in College Station and took in a football game at Kyle Field, y'all have it going on. 
STM317 said:Looks like over 4000 hours for a big cruise ship with the right maintenance schedule:
"To stabilise the oil’s TBN in the Princess Cruises vessels, ExxonMobil recommended an increase in artificial oil consumption of 76 litres a day above current natural consumption.
Without these additions, the oil’s TBN would have reached an excessive level after approximately 4,000 hours, requiring a full sump change. Using artificial, consumption to stabilise the TBN of Mobilgard™ M50 on each of its seven ships, Princess Cruises was able to extend the oil change interval, with overall volume savings of over 81,000 litres in the first year. This equated to significant financial savings, with total lubrication costs falling by more than $100,000."
Does an "increase in artificial oil consumption" mean that they suck lubricating oil out of the crankcase and feed it to the engine as part of the fuel mixture and replenish the lubricating oil with a corresponding quantity of fresh oil?
Gotta say that while there is no simple answer to my question, I have learned a lot about the topic. The size and quantities are fascinating for a guy who spent the last 20 years of his career working in microns.
In reply to NOHOME :
I interpreted it as " they suck lubricating oil out of the crankcase and feed it to the engine as part of the fuel mixture" to make up for the lubrication lost to old oil properties, without replenishing it with fresh oil. Ran it from the top to the bottom of the mark on the dipstick maybe?
In reply to 11GTCS :
Hey, thanks! I loved that school. I was Ocean Engineering '23, I'd probably attend Corpus's program if I had it to do over again (not just because of the ship, though)
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