Trawler Forum

Trawler Forum (
-   Power Systems (
-   -   Oil Change Frequency (

Doc 12-07-2010 07:13 AM

Oil Change Frequency
I have always changed my boat's oil, whether gas or diesel, at the recommended interval or once a year. I have changed the oil with as little as 20 hours on it if it was a year old. Now I am wondering if it is really necessary to*do it that often. I have heard the arguments that boat engines sit in an environment where the ambient temperature and humidity change which can cause moisture build up.

What brought this to mind is my new car, a Buick*Enclave. It tells you when, based upon your usage, to change the oil. Right now for example I have over 8,000 miles on it and the car tells me that I have 20% oil life remaining. The monthly Onstar report sent via email* gives me tire pressures, etc., and*forecasts*the first ever*oil change will be needed*at 10,800 miles.

My buddy the graduate petroleum engineer says that he has always thought that we changed oil too frequently. It wasn't that long ago that I, without fail, changed every 3,000 miles.

Is the environment of a boat engine or whether it is gas or diesel*that makes the difference or are we throwing money away?

Fotoman 12-07-2010 07:20 AM

RE: Oil Change Frequency
I think we do change the oil too frequently but then again the consequences of bad oil in an engine are a lot more costly. So bottom line we are probably throwing money away so we don't have to throw away a lot more money.

Chrisjs 12-07-2010 07:26 AM

RE: Oil Change Frequency
I usually change oil at the end of the season here in New England - typically that means about 120 hours. I often hear the figure of 100 hours quoted. But the specs for my Cummins 6BTA5.9 (280HP) actually indicate changing at 250 hours, and a recent response from the Cummins tech. was that in regular use, 300 hours is OK. This is more relevant to us this year as we expect to clock several hundred hours on our Bahamas winter cruise!!

Delfin 12-07-2010 07:20 PM

RE: Oil Change Frequency
For $20.00 or so, you can have the oil analyzed to determine whether it needs to be changed or not.* I installed a Puradyn, which I am very happy with, and this year instead of changing the oil, I tested it for the additive package, metals, water, etc.* Prior to changing the Puradyn filter, which sucks up about a gallon of oil, it tested like new.* After changing the filter and adding a gallon I feel I am fine going another year.

The practice of routinely analyzing the engine oil can be a great way to identify when you are getting close to a more serious problem as the metals content goes up with wear (well duh).

sunchaser 12-07-2010 09:17 PM

RE: Oil Change Frequency

What is the advantage of not changing your oil according to the Cat recommendations ?

jleonard 12-08-2010 06:06 AM

RE: Oil Change Frequency
I go one new england season which is 100 to 150 hours roughly for me.
I have a Lehman that requires an oil change in the injection pump and I do that at roughly 50/60 hours.

Delfin 12-08-2010 07:28 AM

Oil Change Frequency
Sunchaser, the only advantage of not changing the oil is not changing the oil.* The only reason to even consider it is if the oil (synthetic in my case) is chemically identical to new oil, which I test to verify.* The SOS test I use is the more expensive one which provides data on the additive package, H20, lubricity, metals, etc.* In talking with the lab, they indicated that they couldn't differentiate the sample I sent after 200 hours with oil that had been run for 20 hours on an engine that had been broken in.

I'm not recommending it, just letting you know what I do.

Incidentally, I have no intention of experimenting over the long term, just extending the interval a bit.

-- Edited by Delfin on Wednesday 8th of December 2010 08:30:03 AM

Phil Fill 12-08-2010 09:58 AM

RE: Oil Change Frequency
The rule of thumb as state above is 100 hours and/or when stored for long periods of time.* However, that can vary!*

Each year I have the oil analyzed as we do not put that many hours on the engine and/or gen set.* My reason of late is the new lower sulfur diesel can/may damage older seals and hoses.* Two years ago the seal on the fuel pump failed on the 671 so it was pumping diesel directly into the oil pan. This can also could happen on our old gen set.*

I noticed the oil level on the 671 was raising and the oil looked to be getting cleaner.* So I called my mechanic and he knew right away the reason way.* There was 1+ gallons of diesel in the oil. I was luck to notice as of course the oil is not lubricating as well but the biggest concern is the engine could run away if the level as high enough.* So when checking the oil make sure its not to full as well as being low.

We very seldom go over 40 hours, last year a whole 4 hours on the 671, so we change the oil based on the oil sample. The gen set we changed as we do run during the winter and this year the main dock power panel blew. Monday night my diesel mechanic came*check/listen to*the Webasto, take the oil samples and talk about air leaks and air filters.** Also make sure the oil meets the mfg requirements and weight.*
So I am waiting for the oil analysis results.* *


FF 12-09-2010 05:04 AM

RE: Oil Change Frequency
I have yet to meet the engineer that claimed ,

" Your engine crapped out because the oil was to fresh!!

Almost no hours will leave acids (blowby) in the oil , that are taken care of by the 15% of the oil that is an addative package .

The package dies over time , just time , so needs to be really fresh for out of service times.

Marin 12-09-2010 10:59 AM

RE: Oil Change Frequency

Doc wrote:

Is the environment of a boat engine or whether it is gas or diesel*that makes the difference or are we throwing money away?

Your car gets a lot of use.* In some ways this is better than having the engine just sit for weeks or months with no use.* Of course what the OnStar system or onboard system is telling you with regards to oil change interval is just based on time or miles or both.* I rather doubt there is anything on the vehicle that is actually sampling and evaluating the oil for contaminants.

The issue with marine engines is that in recreational service they tend to sit for very long periods of time.* If you look at the boats in the marina around you the chances are that most of them never seem to go anywhere or get any attention.* In some places you can't use a boat during the winter even if you wanted to.

While I don't understand all the causes and effects, the lube oil in a diesel gets contaminated by combustion by-products.* When the engine is used regularly this isn't a problem but if an engine with "used" oil in it is allowed to sit for a few months or longer, the acids that form in the oil as a result of the contaminants can attack the metal in the engine and pit the crank shaft, connecting rod journals, etc.* This is the main reason for the "change the oil before laying up the boat" rule.* Fresh oil hasn't been contaminated yet, so there won't be an acidic condition in it that can attack the metal.

As far as how often to change oil, I adhere to the notion that fresh oil is not bad for an engine.* The oil change interval for our old FL120s is 200 hours.* We change it every 100 to 150 hours.* Compared to all the other costs associated with boating, lube oil and filters are free.* And the old oil is recycled into all sorts of products, so it's not like we're screwing up the planet by changing the oil.

I have no doubt that one could make a scientifically-based case for extending the oil change intervals for cars and boats.* You could factor in ambient temperatures and the heat factor resulting from the work the engine does under different loads and power settings and*calculate the pressures exerted by the connecting rods on the crank journals under*different loads*and have all sorts of fun proving that the optimum interval for changing the oil in your boat is exactly*382.78 hours.* Or in your car 9,133.7 miles.

I'm not that interested.* All I care about is maximizing the service life of the engine and keeping things simple.* I have other things more important that oil change intervals to get all anal about.* As I have yet to have a mechanic tell me that fresh oil is bad for an engine, we change the boat oil whenever it's convenient to do so at some point between 100 and 150 hours and we change the oil in all our vehicles, old and new(ish) at 3,000 miles.

Could we go longer?* Undoubtedly.* Do I care? No.


RT Firefly 12-09-2010 11:12 AM

RE: Oil Change Frequency
** One other thing to consider and I don't know how relivant it is is the fact that a boat engine "works" 90+% of the time whereas a car motor only *"works" about 40% of the time (the rest of the time it's just coasting).*

Carey 12-09-2010 11:42 AM

RE: Oil Change Frequency

RT Firefly wrote:

One other thing to consider and I don't know how relivant it is is the fact that a boat engine "works" 90+% of the time whereas a car motor only *"works" about 40% of the time (the rest of the time it's just coasting).

Good point RTAnd in addition, they run for the most part at a constant RPM, without all the periods of acceleration. I don't know what the bottom line effect on the oil would be in comparison though. Does anyone know of a comparison between diesel truck and boat oil properties after 100 or 200 hours???


sunchaser 12-09-2010 01:14 PM

RE: Oil Change Frequency
Cat routinely does oil samples/studies*for customers on heavy equipment engines for off road as well as for the same marinized versions. They havelots of data collected over the past 30 years. Cummins does similar.

There is such a variation in marine use that*the studies*become use oriented. Take for instance a ferry vs a large seldom used pleasure craft. Load, hours of use and PM programs come into play. For off road, most equipment Cat is following is on a high use basis, nearly 24/7. Oil temperatures are higher ( and seldom cool off) than a marine application thus generally longer wear.* A dozer or truck may accumulate as many hours in a year as a pleasure boat would in 20. Oil changes for off highway can be several times per month*whereas on our trawlers sometimes only yearly. Bottom line, it is tough to compare oil analysis for marine to off highway.

RickB 12-09-2010 01:20 PM

RE: Oil Change Frequency

Carey wrote:And in addition, they run for the most part at a constant RPM, without all the periods of acceleration. I don't know what the bottom line effect on the oil would be in comparison though.
* I don't know much about trucks but the generator engines on ships run constant speed and generally constant load for up to 30,000 hours between overhauls and oil isn't even sampled until around 700 or 800 hours in operation.

Oil change intervals*can exceed 10,000 hours.*Good filters, the use of a centrifuge to remove water and solids, and topping up*keeps the*oil within spec and unless something goes wrong with the engine to dilute the oil with fuel or puts metal or seawater into it, it can just keep on lubeing for a long long time.*

Tidahapah 12-09-2010 02:00 PM

RE: Oil Change Frequency
As long as they are not CATs.
On this new generation of small Anchor handlers we have (60 mts) we have 2 x 3516s as mains and a few C17s as gen sets.
No purifiers except for fuel.
Oil changes are done every 500 hrs comming ready or not. 1000 hrs on the 3516s
man in 40 years at sea I have never seen so much LO being changed out. yeah we still get oil analysis checks done but this change period is all at the insistance of CAT.
Just on the mains alone we are using over 10,000 lts of new LO a year.(each engine)
Mind you at about 1000 hrs you can visually see the oil degenerating and the filter diff starts to increase, require at least one filter change before oil change.
Talk about a disposable society.


RickB 12-09-2010 02:16 PM

Oil Change Frequency

Tidahapah wrote:Talk about a disposable society.
Good to see you chime in on this stuff, I always wonder if you are sitting there someplace just shaking your head when I post something about ships ... with you around I can't make up any good sea stories!

I wonder if the manufacturer's legal departments are not behind a lot of this. Between fights about why something broke or wore out prematurely and the emissions rules they probably just figure on letting the operator take the costs.

Which is kind of funny when you think about all the effort to reduce cylinder lube oil consumption on the slow speeds. But that is also driven by the emissions folks I guess, and the cost of cylinder oil. I was just reading a report that stated a 10 percent reduction in cylinder lube consumption was worth USD $30,000 a year savings for one of their ships!

*Re the 3516, it's interesting that CAT extends the oil change interval up to 4000 hours on their mining trucks (so I read) if you install their "oil renewal system" that burns off then replaces a set amount of lube at some interval. What that tells me is that they know that replacing enough of the additive package to maintain TBN and such if combined with good filtration is good enough but they don't trust marine operators to do that. It's good enough for Wartsila and other manufacturers though.

-- Edited by RickB on Thursday 9th of December 2010 03:30:22 PM

sunchaser 12-09-2010 02:28 PM

RE: Oil Change Frequency
Rick B --* Delfin raised the synthetic oil question a few posts ago - in* your experience do many of the long life gensets use synthetic oils?

Off highway engine oils*suffer heavy dust loading, even with very good intake and oil circulation filters. The potential problems from dust loading creates a different oil change scenario than say a boat engine or genset.

I am always amazed at how dozers can get 15,000 + hours on their engines given the dust cloud they work in. Ditto farm tractors. Lots of good filters, both air and oil "cure" the problem

RickB 12-09-2010 02:57 PM

RE: Oil Change Frequency

sunchaser wrote:

Rick B --* Delfin raised the synthetic oil question a few posts ago - in* your experience do many of the long life gensets use synthetic oils?

I don't know anyone running synthetics in the gensets. On ships we run the oil through a centrfuge to remove the heavy nasties and just rely on onboard testing and makeup oil to keep it "fresh." We use too much oil to just toss it away on an arbitrary schedule. That stuff is expensive!

One of our boats with a pair of MTU-4000s just switched over to synthetic to try and increase the change interval and that oil is lab tested every couple of hundred hours and we just got the first test back so it will take a while to establish a trend or determine if it is worth it. I will let you know if we find anything interesting.

My personal take on oil changes on small boats like our trawlers is change it once a year, especially if the boat is laid up for months during the winter. If it is being used constantly, change it when the warranty demands it. If there is no warranty to worry*about, make your engine take a Rorschach test. Change it when a drop on a piece of white newspaper or filter paper shows a heavy soot load or a wide ring around the black dot. If you want to know how to interpret that test, start practicing with a drop of oil every 10 or 20 or 50 hours and save the papers to compare ... you will see a change in the size and color of the stains as usage increases.


Nomad Willy 12-10-2010 06:56 PM

RE: Oil Change Frequency
Several things that have not been mentioned:

1. Oil analysis is good but I think there must be also some kind of mechanical or physical change in the properties of oil that does not get analyzed. I seem to recall that over time the length of oil molecules decreases as the oil "wears down" and the length of the oil molecules is what makes oil slippery.
2. Years ago I recall Jaguar owners complaining about oil consumption and they were told not to worry as it was from cylinder wall lubrication loses and it should be considered a small price to pay for reduced wear of well lubricated parts.
3. Carbon buildup in lube oil is a serious problem and much more so in diesels than gas engines. Since carbon is an abrasive changing oil sooner is always an advantage.
Carbon is what turns diesel engine lube oil black and we've all seen how fast our oil turns black. I change real often. Marin dosn't think much of my habit of changing oil 2 out of three times without changing the filter but wind up changing the oil more often as it's so easy. I have a hand operated pump and to pump out whats in the crankcase and replace it only takes a few minutes. I change my oil 3 or 4 times a year this way.
4. Unless you have extremely hot turbos synthetic oil (lube) is not only unnecessary but probably serves no useful purpose whatsoever. As oil becomes more and more scarce there will come a time when synthetic will be cheaper than dino oil.

I've been off line for some time due to computer problems. I've still got an airport problem to my i-Mac but I can now poke my head up on my wife's PC. Very slow.

Marin 12-10-2010 07:27 PM

RE: Oil Change Frequency

nomadwilly wrote:

2. Years ago I recall Jaguar owners complaining about oil consumption and they were told not to worry as it was from cylinder wall lubrication loses and it should be considered a small price to pay for reduced wear of well lubricated parts.

This lubrication system was*developed *by the British car manufacturers and was known by the industry as the "Total Loss" oil system.* In addition to cylinder wall lube loss, this system also incorporated deliberate gasket and seal*leaks strategically placed throughout the engine to ensure a fairly rapid lube oil loss.

The theory behind "Total Loss" was that the operator would be forced to add oil at relatively short intervals to compensate for the loss, thus ensuring that the engine oil would be replenished with fresh oil on a continuing basis.* This in turn would ensure a longer engine life.

The British were so successful with the Total Loss oil system that it was adopted by several US vehicle manufacturers in the 1950s, the most notable being Harley-Davidson.

While the British tend to take credit for developing the Total Loss system there are some who claim they "stole" the idea from the aircraft engine industry.* Total Loss, or a version of it, had been used first in rotary and then radial engines since before WWI.

Vehicles (and aircraft)*that incorporate*the Total Loss oil system are easily identified by the puddle of oil that accumulates under the engine after it's been switched off.* In fact from the late 1940s until about 1975, many British vehicles when sold new came with a shallow pan to place under the engine to catch the oil and prevent the*staining of driveways and garage floors.* For example, the Land Rover Series III-88 that I purchased new in 1973*came with*a clever folding drip pan*for this purpose that could be stored in the tool compartment under the driver's seat.* I think I still have it somewhere.

All times are GMT -5. The time now is 10:41 PM.

Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012