It’s all about the hydrodynamic film thickness provided by the oil. As long as that film is thicker than the major dimension of any asperities like surface roughness or oil borne particles that get trapped between the contacting surfaces then all is well from an accelerated abnormal wear point of view. We call it the lambda ratio which is film thickness divided by asperity size. You want a number greater than 1 which means no metal to metal contact so no wear. Anti wear additives like tricresyl phosphate in the oils we have nowadays build up a protective layer on the metal surfaces in an effort to make sure the lambda ratio stays greater than 1 and fine filtration traps extraneous particles that might defeat this. Our science is good and the engineering supports it. Again the oils we get to choose from are all good quality nowadays. Very good really and they can last very long times under our normal engine running temperatures without any thermal degradation.
On Sat, Aug 31, 2019 at 4:55 PM Russ & Melody via CnC-List < [email protected]> wrote: > > Hi Ron, Wade & Bill, > > It seems engine oil can be an emotional topic. For any experienced > yachtsmen out there who have a system and are happy with it, please don't > change any practice that works for you on my account. > > For newbies and others, I typically advise that engine oil is the cheapest > thing we buy for our boats. Change it as often as you feel like it. My > routine was every fall except every other if I had less than 100 hours on > that year. > > The filter gets changed much less. > Filter fun facts, filtering performance gets better as it gets dirty and > the blackness of oil is unburned carbon too small to filter (not harmful). > > When long distance cruising I used to save the used engine oil to use as > the 10:1 oil ration for my Seagull outboard. It wore a diaper when loaded > on the rail to keep the deck from dark stains. Livin' on the cheap, doncha > know! > > The main degradation factors of engine oils are heat & pressure followed > by combustion products (blowby) & moisture. A properly sized diesel runs > much higher loading than a gasoline transportation engine. > Thus the hierachy of engine oil can be stated as: > GOOD - gasoline engine rated oils > BETTER - diesel engine rated oils (higher detergent additives than gas > rated) > BEST - 100% synthetic feedstock oils > > So, Rotella Triple T is great for all of our applications. The main reason > I run synthetics though is for heat tolerance. If you lose cooling capacity > and don't notice right away then when "something smells HOT!" happens the > synthetic oil may be the difference between an inconvenience and disaster. > > Syn is not for all cases of course. Last winter a buddy was on a bike > trip, 1200 CC air cooled, to Mexico and wanted to "treat it right" by > putting fresh synthetic in. I said, "No. No. Don't do that. Synthetic is > too slippery for the wet clutch. Use something that has the JEMA rating, > like Rotella Triple-T." He did a 15,000 km trip on that oil change with > only putting in top-ups. Not recommended at all but demonstrates the > quality of regular rated diesel oil. > > Cheers, Russ > ex-* Sweet *35 mk-1 > > At 10:36 AM 8/31/2019, Ronald B. Frerker via CnC-List wrote: > > Content-Type: multipart/alternative; > boundary="----=_Part_716484_1681950774.1567272988188" > Content-Length: 1916 > > > > I'd been told by a mechanic, that one shouldn't put 100% synthetic oil in > an old vehicle that had been using regular oil all its life. The claim was > that it would clean the engine too good and it would start leaking. > It's highly recommended for newer cars of course. > I would presume the same would be true for marine engines, unless the fact > that they're diesels would make a difference??? > Anyone else ever heard that story and have heard whether it's true or not? > Ron > Wild Cheri > C&C 30-1 > STL > > _______________________________________________ > > Thanks everyone for supporting this list with your contributions. Each > and every one is greatly appreciated. If you want to support the list - > use PayPal to send contribution -- https://www.paypal.me/stumurray > > _______________________________________________ > > Thanks everyone for supporting this list with your contributions. Each > and every one is greatly appreciated. If you want to support the list - > use PayPal to send contribution -- https://www.paypal.me/stumurray > > -- Sent from Gmail Mobile
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