Hi Chuck, I spent many years of my career supervising and develop[ing laboratory oil analysis techniques for the Canadian Navy. To answer your specific question; samples should be collected just after shut down, while the oil is warm and well mixed. There are many things to consider when using laboratory oil analysis to predict state of wear or time until failure. First of all, most normal wear particles are small, typically less than 1 micrometer in major dimension and appear as flat platelets. Even particles that small escape detection by many spectroscopic oil analysis techniques. Particles indicative of abnormal wear are generally larger than 1 micrometer in major dimension and have irregular shapes such as cutting wear particles which can resemble machine chips. The quantity, size, shape and chemical composition of these particles found in the oil or on the filter element can be very helpful in assessing internal condition. Since most of these larger abnormal wear particles escape detection by the spectroscopic techniques used for oil analysis, examination of particles found on filter elements and mag plugs can be very useful indicators but often tell the story after it is already too late to avoid failure. Any spectroscopic analysis relies on trending so one sample actually tells very little. what the analyst looks for is an increase in any metal content (eg. iron, chromium, nickel, etc) as a function of operating hours since the last oil change. So if you change your oil every fall for example and sample that oil only once during the oil use cycle that will defeat any trending analysis. So since most of us change the oil and filter in our rather small marine engines it is doubtful in my mind whether wear metal analysis is at all a useful indicator. I will suggest, however, that filter debris analysis is a worthwhile effort and examination of debris found on magnetic plugs if you are lucky enough to have one would also be useful. I will note that water contamination of the oil is an issue but save for a coolant leak I don't see that being a significant issue. I also believe that the additive packages in oils that meet minimum API or SAE specs are very robust and consequently it is very unlikely that your oil will become acidic during the normal use period. I will note also that as long as wear particle size and asperities caused by surface roughness are smaller than the hydrodynamic film thickness of the oil between moving parts that your system will not experience significant wear. So fine filtration helps and any oil that meets minimum specs is good. Happy sailing Dwight Veinot C&C 35 MKII, *Alianna* Head of St. Margaret's Bay, NS d.ve...@bellaliant.net
On Fri, Oct 16, 2020 at 9:36 AM CHARLES SCHEAFFER <cscheaf...@comcast.net> wrote: > Oil Testing > > Does the oil sample need to be pulled from the very bottom of the sump to > capture the metals there? > > Chuck S > > On 10/16/2020 7:55 AM ja...@jpiworldwide.com wrote: > > > Hi All, > > > > In a previous life I had to do oil samples on heavy equipment and aircraft > engines (both piston and turbine). Some of these pieces of equipment or > aircraft would run 24/7 so oil samples were taken weekly…(every 100 hours > is a common number for production equipment to be sampled) The oil analysis > would come back from the lab and it would contain information on a variety > of things… the most important thing to the owners and operators of the > equipment was the metal content in the oil. As engines are used (and thus > tend to wea) parts of the engine are “ground off” and wind up in the oil. > By analyzing the metallic content really good analysts could determine > exactly what part inside the engine was breaking down… but usually they > were just looking for the aggregate amount of metal shavings/dust/chips > etc. There is usually some tiny teeny-weeny little bit of metal in the oil > (especially on high-hour engines), but over a certain level or amount of > metal , the managers of the equipment would be concerned and sometimes even > take a piece of equipment out of service and tear the engine down and > rebuild it or replace it. > > > > Another thing they did was determine if there was soot or carbon from the > combustion process, water in the oil, fuel, coolant, dust, dirt, or silica. > All of these were indicative of different problems in the engine. Again, > most tests will come back with some small amount of each depending on how > infinite or precise the sample testing is. As an example if there was > “dirt” or grit, sand, silica etc in the oil, this may indicate bad fuel, > bad fuel filler spout, bad fuel cap, air filter(s), or air filter housing > or hosing. If the sample had coolant in it, then they might look at the > cylinder heads, or if there was soot, valves or rings may be the problem… > all kinds of things can be divined from the oil sample if read by a > knowledgeable person. > > > > Me- I just took the samples, logged the results, and ate lunch 😊 > > > > JP > > > > *From:* Tom Buscaglia <t...@sv-alera.com> > *Sent:* Thursday, October 15, 2020 5:23 PM > *To:* Stus-List <cnc-list@cnc-list.com> > *Subject:* Stus-List Re: Engine Hours > > > I never knew about the oil testing. Just ordered a test kit...thanks! > > Tom B > > At 03:26 PM 10/15/2020, you wrote: > > This is an interesting, timely and informative thread/discussion. We just > recently bought another boat with a large Diesel engine.The former owner > left extensive and detailed documentation. In that documentation are the > results from engine oil analysis that he performed every year, going back 6 > years. I’m starting to try and educate myself on this and will continue > to do the sampling which comes up this November. My initial take is that it > is important for spotting engine wear/maintenance trends. > > Thanks to listers for all the insights. > > Regards, > Dave > 1982 C&C 37 - Ronin > > > On Oct 15, 2020, at 4:18 PM, Josh Muckley <muckl...@gmail.com> wrote: > > I sample my oil and sent for analysis. Costs $20 but the knowledge of > whether or not the oil is good as well as what else could be wrong with the > engine is invaluable. For anyone who cares about the environmental > impacts, not changing the oil is better for the environment too. I use an > over-sized oil filter and the very best amsoil marine diesel engine oil. > This particular oil has a high TBN of 12. IIRC, TBN stand for total base > number, you know base... The opposite of acid. As acids build up in the > oil the TBN goes down. If the person doing the analysis sees that the > trend suggests the TBN (or any of the oil specs) will be too close to zero > before the next oil change, they modify their recommendations. > > > https://drive.google.com/file/d/1MaBnvf4Fc9auz-p_Yw-yp5uh-Z7R4N__/view?usp=drivesdk > > Keeping moisture out of the oil is another key to long life. A block > heater keeps the oil dry, the rings from sticking, the cylinders from > rusting and the boat warm enough to prevent the bilge from freezing. > > Josh Muckley > S/V Sea Hawk > 1989 C&C 37+ > Solomons, MD > > > October is the time to show your appreciation with a small contribution to > this list to help offset the costs. If you want to support the list - use > PayPal to send contribution -- https://www.paypal.me/stumurray > <https://www.paypal.me/stumurray%A0>Thanks - Stu > > .¤º°`°º¤,¸¸,¤º°`°º¤¤º°`°º¤,¸¸,¤º°`°º¤. > Tom & Lynn Buscaglia > SV Alera > C&C 37+/40 > Vashon Island WA > (206) 463-9200 > www.sv-alera.com > > October is the time to show your appreciation with a small contribution to > this list to help offset the costs. If you want to support the list - use > PayPal to send contribution -- https://www.paypal.me/stumurray Thanks - > Stu > > October is the time to show your appreciation with a small contribution to > this list to help offset the costs. If you want to support the list - use > PayPal to send contribution -- https://www.paypal.me/stumurray Thanks > - Stu
October is the time to show your appreciation with a small contribution to this list to help offset the costs. If you want to support the list - use PayPal to send contribution -- https://www.paypal.me/stumurray Thanks - Stu
