Oil change... Make it a double

Jul 2, 2019
102
Hunter 310 Pine Beach, NJ
1) Engine oil is dirtier in a diesel... more acids, carbon, etc than oil in a gasoline engine.
2) Sucking oil out a dipstick tube is less efficient than unscrewing a drain plug.
3) Two or 3 cyl marine diesels do not take very much oil at all.

Put those 3 things together and I have come up with a little extra insurance for my Yanmar 2GM20F. Bought a gallon of oil, which is roughly twice what I need for the fall oil change.

I warmed the engine to make the oil flow better. Waited a few minutes for it to drain down then started the suck out. Same time I removed the filter and poured out the oil stuck in it. Screwed the old filter back on.

When empty I poured a little less than half a gallon of fresh oil in then ran it ten minutes to get it to flush out the original oil. Then I let it drip down for 5 minutes, changed the oil filter and filled with fresh oil again. After running the engine about 10 minutes I pulled the dipstick to adjust the level and was greeted by the freshest oil I ever saw. Cost was an extra half hour and 2 qts sacrificial oil. Now I will sleep like a bear all winter knowing there is next to no acids, particulates or moisture bearing fluid in my engine.
 

Johnb

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Jan 22, 2008
1,420
Hunter 37-cutter Richmond CA
For the first 25 hours after a single oil change (with filter replaced) I can barely see where the oil is on the dipstick it is so clear. This is a 38 year old Yanmar 3QM with about 2500 hours on it. It does take nearly a gallon of oil.
What is the stated oil capacity of your engine?
 
May 24, 2004
7,129
CC 30 South Florida
I heard a curious story the other day. A German girl who had recently moved to the States and purchased a car was told by the dealer that she had to change the oil every 3,000 miles or every 3 months which ever came first. She was confused because she had never heard in Germany about anyone replacing the engine oil. She called her father to verify as perhaps he could have been changing the oil without her knowledge. Her father did confirm that unless an overheat or another event required changing the oil that it was not customary to replace oil that was still good. I knew from a long time that dirty oil is not bad oil as the filter will remove particles of a size that would be harmful. We also now know that oils have been much improved through the years and that many manufacturer recommendations have been upped to 7,500 miles and with synthetics up to a year. Germans are usually very careful of the maintenance of their machinery so what is the truth? I keep a 20 year old truck with over 200,000 miles as a utility vehicle and I only drive it around 2,000 miles a year. Long story short I stopped changing the oil about 4 years ago and I have not noticed any smoking or lack of performance. I will check the level and rub some oil between the thumb and forefinger and it feels thick and oily enough. I know here our car warranties require you follow the manufacturer's recommendations or they will not honor the warranties and I suspect there are economic incentives driving the tale that oil goes bad and must be changed. With boats no oil gets blacker and dirty than an older diesel engine and we change it once a year. Is it really necessary?
 
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May 27, 2004
1,964
Hunter 30_74-83 Ponce Inlet FL
Benny, I don't speak Deutsche,
but I do change the oil and filter on my 30 yo 2GM20F every 100 hours.
(I used to be a pilot)
 
May 17, 2004
5,032
Beneteau Oceanis 37 Havre de Grace
I heard a curious story the other day. A German girl who had recently moved to the States and purchased a car was told by the dealer that she had to change the oil every 3,000 miles or every 3 months which ever came first. She was confused because she had never heard in Germany about anyone replacing the engine oil. She called her father to verify as perhaps he could have been changing the oil without her knowledge. Her father did confirm that unless an overheat or another event required changing the oil that it was not customary to replace oil that was still good. I knew from a long time that dirty oil is not bad oil as the filter will remove particles of a size that would be harmful. We also now know that oils have been much improved through the years and that many manufacturer recommendations have been upped to 7,500 miles and with synthetics up to a year. Germans are usually very careful of the maintenance of their machinery so what is the truth? I keep a 20 year old truck with over 200,000 miles as a utility vehicle and I only drive it around 2,000 miles a year. Long story short I stopped changing the oil about 4 years ago and I have not noticed any smoking or lack of performance. I will check the level and rub some oil between the thumb and forefinger and it feels thick and oily enough. I know here our car warranties require you follow the manufacturer's recommendations or they will not honor the warranties and I suspect there are economic incentives driving the tale that oil goes bad and must be changed. With boats no oil gets blacker and dirty than an older diesel engine and we change it once a year. Is it really necessary?
I’m skeptical that oil changes are that unnecessary. German car manufacturers don’t differ largely from US ones with oil change frequency recommendations. I did find this brief discussion of Germans changing oil yearly or less - Are Germans crazy for changing their oil only once a year...or are we?. Some of their points make sense, like more common use of synthetics and less miles being driven per year. I’m sure there is lots of margin for error in the manufacturer recommendations, but I wouldn’t want to find out how much.

In a year of sailing I usually do about 50 engine hours, which is only maybe 2000 miles in car terms, so I’m not worried about the oil condition from a mileage standpoint. But leaving the contaminants in the engine all winter can’t be good, and even if it’s not too bad I don’t mind the hour and cost of supplies that it takes to replace it.
 
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Jan 4, 2006
6,444
Hunter 310 West Vancouver, B.C.
Same time I removed the filter and poured out the oil stuck in it. Screwed the old filter back on.
And why would you re-use a dirty oil filter if you're going to that much effort to remove as much dirty oil as possible :rolleyes: ?
 
May 24, 2004
7,129
CC 30 South Florida
- Are Germans crazy for changing their oil only once a year...or are we?.

I don’t mind the hour and cost of supplies that it takes to replace it.
At least I'm not crazy, you found an article that supports what I had heard about Germans adhering to a different schedule than we do. I have discussed this with a few other people and most have given me the reason that you have, which is basically "Just in case, how can I go wrong if I have the ability to change it earlier" I understand perfectly but let's face it that reasoning comes more from the Gut than from Scientific Data and it all boils down to the credibility of the Industry Recommendations. What drives the recommendations, historic data and science or economics? We have these Quick Oil Change stations everywhere and I'm sure they are strong proponents together with the Oil companies that oil should be changed 4 times a year. Every automotive shop in the land budgets a good part of their income to quick oil changes. The auto Manufacturers have no interest in going against them and we end up with warranty restrictions that force us to. How do they handle warranties in Germany? The real question for boaters is, how does this translate to how often I need to change the oil in our boats? Today's synthetic oils will last longer than a year and the number of hours that we use our engines is nil compared to automobiles. To be honest I would be more concerned about replacing the filter than the oil even if they say to replace the filter every other oil change. I guess the answer is everyone should do what each thinks is best.
 
Jun 2, 2007
403
Beneteau First 375 Slidell, LA
I like to pump the old oil out, pour in a quart or so of fresh oil to dilute what's left in the oil pan, then pump that out before continuing with a normal oil change. Oil is pretty cheap compared to a new engine.
Can I take moment here to curse the engineer who thought it was a good idea to mount the oil filter sideways?
 

Johnb

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Jan 22, 2008
1,420
Hunter 37-cutter Richmond CA
I like to pump the old oil out, pour in a quart or so of fresh oil to dilute what's left in the oil pan, then pump that out before continuing with a normal oil change. Oil is pretty cheap compared to a new engine.
Can I take moment here to curse the engineer who thought it was a good idea to mount the oil filter sideways?
The last time I changed my oil I got called away after pumping out and before removing the filter so about an hour elapsed in between. Imagine my delight when no oil came out of the filter. That is going to be standard practice in future.
 
Jul 5, 2011
702
Oday 28 Madison, CT
I know a lot of Germans and this lady's story is not typical. "Kleine Inspektion und grosse Inspektion" (minor and major service) take place as per automakers' prescribed schedules. Having said that, there are probbaly few examples of blown engines due to dirty oil as the filters are very good. But......who wants to take the risk?
 
Jul 2, 2019
102
Hunter 310 Pine Beach, NJ
Been engineering in the race car biz for 40 years and owned my share of Porsches. If a Porsche owner found out you did not change oil per the engineers requests (demands), you would be turned in to der vaterland and Porsche would send a rep across the Atlantic to destroy your car and arrest your family including 2nd & 3rd cousins.
 
Sep 15, 2013
707
Catalina 270 Baltimore
I change my oil twice all the time. I started the habit because I always wind up buying way more oil than I actually need. I only change the filter once on the first time. No need to duplicate that misery. I run the engine for about 5 minutes and then drain and fill again. Nice clean oil until the next time you run it. Brand new oil will get black quickly due to soot. It doesn't mean its dirty.
We have boats. You simply can't compare their maintenance needs to cars. If I applied boat rules to cars, I would be changing the oil in my car every 500 miles.
 
Nov 21, 2007
631
Beneteau Oceanis 34 Kingston, WA
Porsche's recommended change interval for synthetic oil is 7,500 - 10,000 miles. They have recommended ("approved"?) only synthetic oil for as long as I have had owner's manuals (+/- 20 years). When I raced (not Porsches), I changed my oil about every 200 miles, but those engines were run a lot harder than my diesel is. YMMV.
 
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Oct 22, 2014
20,995
CAL 35 Cruiser #21 moored EVERETT WA
Raced... Got to hear the stories...
Maybe we can rendezvous in Port Hudson again. This time on purpose.
 
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Mar 20, 2016
594
Beneteau 351 WYC Whitby
Most cars now use synthetic oil long life , mobil 1 or castrol edge meet the spec. My last 2 cars state in manual 18,000 km or 1 year or 11,000 miles and it must be long life mobil 1. The germans have been using this spec for 20 years porsche , mercedes , volkswagen and even gm (GM-LL-A-025 ) LL meaning long life