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valhalla360 · 10-06-2019, 10:14

Quote:

Originally Posted by a64pilot

Nothing ever averages 60 mph, actually less than 30, that sitting at a stop light really kills average speed.
we put over 50,000 miles on a car each year the first couple of years we owned it, so of course that was mostly all highway miles, and that car tracks average speed, and its average was almost always in the 20's MPH.

So triple your example

20 mph would be typical of fairly heavy congestion. I was showing a best case scenario, for rural drivers mostly freeway. 60mph average isn't too far off. While I didn't have an automated system, back when I commuted, it was 2 miles from house to freeway (mostly 55mph road) and 1 mile from freeway to office with 30miles between..typically at 75mph. I was pretty close to 60mph and that was near ideal conditions for a motor where it gets up to temp and stays there.

If it's really 20 or 30mph average...then that only makes the 500hr idea even more extreme.

Ken Z · 10-06-2019, 14:38

change oil at 200 hrs. and filter, and have little worries.

alctel · 10-06-2019, 14:45

My old Yanmar 2QM20 says 50 hours between oil changes, but I've been extending that to 100. Seems ok.

Compass790 · 10-06-2019, 16:42

So I guess you didn't pay to read the study then? Pity I'd value the results of the Society for Automotive Engineers study over some guesses.
Yes studies can be slanted to reflect the wanted outcomes of the funder, thats why you read the study to see the methodology used & try to judge if it's fair.
Bottom line is it's easier & safer if there is no proof otherwise to follow manufacturers recommendations but if rigorous scientific testing proves that there is no detriment to engine life to extend the recommended oil drain interval why not do it?
Fair point that the study applied to trucks & not boats so different operating temps. The long drain oils sold here have high TBN no.s such as Valvoline 15w-40
Doubt that the oil manufacturer would claim long drain intervals if the oil couldn't do that as there would be a risk of getting sued.
However since i didn't pay to read the study I'll continue to change my oil at 150 hrs ( yanmars interval is 100 hrs but it had a crude metal leaf filter that i changed to remote spin on type )
Enjoyed the debate, oil always fires people up.lol

**Jim Cate** · 10-06-2019, 18:35

Quote:

We change oil because it gets soot laden, soot is carbon, and carbon is very abrasive, oil is still fine, but full of wear causing soot particles.

A64,you likely know more about this than I do, but the above statement seems a bit suss to me. Carbon is not inherently abrasive in all its forms. Graphite, for instance is used as a lubricant, and it is 100% C. And soot? I dunno,but soft soot, like from candle flames, seems pretty non-abrasive to simple inspection. Do you have data that says it is abrasive? And I suspect that there are different forms of soot, perhaps related to the temperature at which it is formed, and they may well have differing degrees of abrasiveness. Kinda complicated, eh? But I'm left wondering if black implies high wear characteristics in lube oil.

And then there is the factor of particle size. If they are small enough, even abrasive particles won't cause wear. I've never seen an analysis of carbon particle size distribution in diesel lube oil, but I'm wondering if this is really a serious contributor to our marine diesel engines wearing out. I keep remembering that our engines very rarely wear out in the conventional sense. More often it is other factors that lead to their demise... corrosion, overheating, hydrolock damage, etc.

They are all kinda silly concerns IMO, for the annual change requirement supersedes the hour requirement for most yotties!

Cheers,

Jim

**Wotname** · 10-06-2019, 18:54

Quote:

Originally Posted by Jim Cate

.......

And then there is the factor of particle size. If they are small enough, even abrasive particles won't cause wear. I've never seen an analysis of carbon particle size distribution in diesel lube oil, but I'm wondering if this is really a serious contributor to our marine diesel engines wearing out. .......

Regarding particle size, at some point, the smallest particles becomes a polish - no????

They are all kinda silly concerns IMO, for the annual change requirement supersedes the hour requirement for most yotties!

Cheers,

Jim

Yep, the calendar dictated most of my oil changes in the past but maybe the cruising sailor has morphed into a cruising motorer in recent decades.

Ya might have to modernise Jim and find that start switch

**a64pilot** · 10-06-2019, 18:55

Better explanation of the abrasive quality of Diesel engine oil soot than I can explain, and maybe is more believable than I am.
http://www.aei-tech.com/products/bts...cant-oil-soot/

Compass790 · 10-06-2019, 19:00

Quote:

Originally Posted by hpeer

I have a slightly different dilemma. My 35 year old Volvo MD7 says 20/30 weight oil (above 10°C) and 10 weight below, and change every 50 hours. First, where I am I can’t get 30 weight oil let alone 10. I can get either 10w-30 synthetic or 15w-40 classic oil. Engine has about 1,000 hours on a full, professional rebuild. Previously I’ve always changed oil at 50 hours or real close. It’s right black by then.

I’m looking at a longish trip where I will have in-route oil changes. 3°C water.

I’ve stocked up on the 15w-40, and a bunch of oil filters. I think I’ll extend the oil change to 100 hours. Changing oil underway, open ocean is just too much fun, I need to resist the urge. (Scarc)

Then there is the transmission which also wants 30 or 10 weight. I can probably find a couple of quarts of that in a non-diesel blend.

I wouldn't sweat on using the classic 15w-40 in your Volvo instead of 30 as long as it has a C in its SAE rating. C stands for compression ignition engine. I've been using 15w-40 in our 1980 yanmar for 5+ years in both engine & gearbox with no issues, yanmar calls for 30 but seen many similar era/design engines running for decades running on 15w-40. I'm currently using 20w-50 CF but that's just because it was a good deal
I'd prefer straight 30 weight for the gearbox ( at a guess) but can't be bothered hunting it down. In our country you can get it in specialist lawnmower/small engine shops but don't know about USA.
Pretty sure ( without doing a study lol ) 100 hrs wont be a problem either

**a64pilot** · 10-06-2019, 19:03

I had always read that if you can clean oil down to 5 microns or better that you will remove the vast majority of particle sizes that will cause wear, if the particle is small enough it will fit inside of the oil film and cause little to no wear.
Regular filters can only get down to about 30 microns, high bypass filters can go down to 5 or even smaller.
This is however a very good article that I have little to disagree with from a brief scan, however it says most wear is from 0 to 20 micron particles, my assumption is that’s because a regular filter removes bigger than that particles, so not many are present.
But I just gave it a quick scan, didn’t really read it yet
http://citeseerx.ist.psu.edu/viewdoc...=rep1&type=pdf

**Wotname** · 10-06-2019, 19:13

Quote:

Originally Posted by a64pilot

Better explanation of the abrasive quality of Diesel engine oil soot than I can explain, and maybe is more believable than I am.
What Is Lubricant Oil Soot? - Analytical Engineering, Inc.

Hmm... I think I prefer your explanations about all things engine related A64.
Not only is your logic sound (IMO), you use words that I can fully understand.

Your attached article has at least a dozen words that cause me to reach for my dictionary and I like to think I have some technical aptitude.

So it is more believable - I dunno cause right now I can't understand it - I will stick to believing you for awhile yet!

**a64pilot** · 10-06-2019, 19:15

Quote:

Originally Posted by alctel

My old Yanmar 2QM20 says 50 hours between oil changes, but I've been extending that to 100. Seems ok.

Does this engine have an oil filter?
If not that’s likely the reason for the short oil change interval.

Aircraft engines for example if they have a filter the oil change interval is 50 hours, if not, 25 hours.

Many times marketing has more to do with service intervals than getting the max life out of the engine, an engine that requires servicing less often is easier to sell than one that requires more frequent servicing, and of course it will make it through the warranty period easily.

You’ll get a good long life out of your engine if you change it’s oil at 200 hours, and Fram oil filters will work OK too.
Just I believe that an engine will last longer with more frequent oil changes, using good quality oil and filters, but the cheap stuff meets requirements.
It may not be worth it to you, most people, especially ones that buy new boats will never wear out an engine, to them frequent oil changes are a waste of time and money, they won’t own the boat when the engine wears out.
But some of us are driving around in boats with engines over 30 yrs old, and we need to try to get them to last as long as possible. If that’s you, then I believe you are better off changing oil more frequently.

fivecapes · 10-06-2019, 19:29

A more recent study https://link.springer.com/article/10...249-016-0704-9 on the effects of soot on the boundary layer.

This study suggests that there is soot as hard as metal engine parts and hard enough to abrade the engine.

Soot, like diamond, is just another form of carbon.

Compass790 · 10-06-2019, 19:51

Thanks for posting links to studies A64 & fivecapes. Looks like some good education in there, needs a bit of time to grapple with :-)

**Jim Cate** · 10-06-2019, 19:57

Quote:

Originally Posted by a64pilot

Better explanation of the abrasive quality of Diesel engine oil soot than I can explain, and maybe is more believable than I am.
What Is Lubricant Oil Soot? - Analytical Engineering, Inc.

OK, thanks to you for posting that, and to fivecapes for his links as well. The case for detrimental effects of soot in oil is pretty well shown, and my doubts are relieved. I don't understand what boundary layer erosion is, but can accept that it can cause severe wearing of bits. I find it interesting that they attribute the wear (I think) to 1000 Angstrom particles... that's damn fine stuff and not what I intuitively think of as bad acting. Certainly not filterable in the normal sense.

And BTW, like Wottie, I find your engine related ideas well founded and practical... completely believable. I meant no disrespect whatsoever in my queries.

Jim