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Oil change frequency


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Our auto service centre told me that if I shorten the time between oil changes my car would see a significant extension in expected mileage. I admit to thinking yep, he's looking to make a few extra dollars..

But then there is a retired marine engineer with a canal boat here, and his boat has a 120hp Volvo diesel in it with 23,000 hours on it. He claims to have done no major work on the engine but does an oil and filter change every 100 hours maximum.

Makes you think.

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If it is easy to change, then regularly changing the Oil will add years to the engines life. You don't even need to use a good oil. The Cheap value packs will do just as well as expensive oils. It is all about the little particles of carbon in the Oil. They are sharp and abrasive. Diesel Oil mainly differs from petrol engine oil , in that it has a lot more detergent in it. The detergent causes the Carbon particles to remain suspended in the Oil and then the larger ones can be trapped in the Filter and the finer particles get removed with the Oil change.
However! Just like a Battery Bank with the rule of thumb of 50% discharge, the same applies to Oil changes. There is a point in which the cost of changing outweighs the life increase. As an extreme example to make that comment easier to understand, There would be no point in changing the Oil hourly because the cost and hassle of doing so would eventually outweigh the life increase of the engine, because eventually, no matter how clean the Oil, the engien will still wear out.
You have to figure a compromise of longevity against cost and hassle of oil changes.
For many sail boats, engine hrs are not high per year, so a yearly change is all the is needed.

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But there is another issue which is, so I have been told, that once oil has whizzed around inside the engine for a few hours it turns acidic as a result of the combustion/ignition process. Theoretically then even if you only do 30 hours engine runtime over the summer and zero hours over the winter you would still be advised to change the oil at the end of each summer so that the engine doesnt sit idle over winter with contaminated oil inside.

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The oil itself does not turn acidic, but it carries around Acids. However, that is mainly Petrol Engines. For every 100ltrs of air the engine sucks through, ruffly 1ltr of water is produced and 1/10th of a ltr of Sulphuric Acid.
For Diesel, sulpher was removed from Diesel and thus thew Acid is not produced as much as it used to be.
Add to that, the Additive pack in a container of oil has an Acid neutralizer component in it. Usually a form of Zinc.
The idea of replacing once a year, usually at end of season, is so that any condensation in the engine oil is removed and the new oil has better Acid neutralizer and so your engine is then sitting pretty for the Winter months.
As long as you use an oil that meets the specs of the Engine manufacturer, you don't have to go expensive if you regularly change it.
However, those cheap Oil packs JUST meet spec and it is best to ensure you don't go for extended periods between changes.

For the engine I had, it held a lot of Oil and it was a major PiA to change. So I used a top end Synth Oil. I do the same with my Vehicles as well. For instance, with my V8, I change the Filter every 10k Kms and the Oil every 30k Kms and have even gone as far as 50k Kms once. 
 

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but then should be changed at 10000 km's to avoid opening bypass.

Fact or fiction?

Fiction. The Fiction will cause Friction. ;-) The Filter is all about surface area of the paper material and thus how much the filter can hold before the bypass opens and just lets the dirty oil flow around the engine.

Leaving the filter too long will mean the chance of the by pass opening is far greater and the dirty oil free flowing is far greater than any very fine bits that manage to get through the filter.

 

There are good filters and there are great filters. Very rare that you come across bad filters. With the normal brand names around, it is more about the amount the filter can hold.

 

Many of the Long haul trucks use multiple remote from engine fitted filters and some use " Spinners" which are centrifugal filters.

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Km  The modern truck is now 30 thou before an oil change,and with auto box start n go,the old road ranger had sit for a few minutes clicking hi/low to warm it up. 

Back to Chrics canel boat,after siting there for what 3 or 4 months I think it would make sense to change

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Back to Chrics canel boat,after siting there for what 3 or 4 months I think it would make sense to change

What I'm doing is to change the oil and filter at the end of the season, run the engine for 10 minutes to circulate the new stuff all around and then lay up for the winter.

I am just really intrigued that my canal boating Dutch marine engineer friend got 23,000 hours out of his Volvo and it's still going strong. I've not heard of those number of hours before on a toy diesel, and he has the engine logbook to verify it.

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Race cars are anal and need reliable motors, they change the oil in them frequently.

 

Litre class motorcycles, most performance ones, have some reasonably advanced motors these days. All recommend frequent oil changes for motor longevity. In the case of my 1079cc Kawasaki not hugely fancy motor, every 7000km. I recently did 4500km in under 3 weeks.

Depends on the Race. For instance, The V8 Supercar engine used for Bathurst 1000, was designed to last just 1300Km. These kind of engines have what is called a Dry Sump and the Oil is pumped from a larger reservoir held somewhere else in the Vehicle. These kind of engines go for Synthetics that have very high wear pressure ratings.

F1 engines have such a fine tolerance of components that when the engine is cold, the thing is seized solid. The engine has to be pre heated before it can be started. The Oil used in those engines are synthetics designed to handle very high temperatures.

 

Small engines like those in Bikes (4 stroke of course) often use a very specific oil that has no detergent in it. These will be the Bikes that do not have disposable Oil Filters. This includes the small 4 strokes on Motor Mowers and Outboards. They use an Oil that allows particulates to settle to the bottom of the Sump and when you change the Oil, you are also removing the particles. The detergent in Oil is designed to suspend particles within the Oil so as it is taken to he Filter to be removed. Diesel Lub Oil has a lot more detergent in it than Petrol Lub oil. You can use diesel Lub Oil in a Petrol engine, but unless a multi vehicle oil, it is not advisable the other way around.

 

 

The modern truck is now 30 thou before an oil change,

If one thinks about it.  Long Haul truck clocks up so may Ks each week, that if it were just 10K, it would be in the shop every 4 or 5 days.

Engines that do long periods of operation can actually last far longer because the anti friction additive used works best when the engine is hot. Engines doing short work wear much faster because they spend more time warming up.

And yes, I have been a major proponent of start the Diesel and get it in gear as soon as possible and let it warm up under load. Which causes it to warm faster than idle warm ups.

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Many of the larger freight carriers are in to bypass filters, where a small proportion of oil flow is directed through a finer filter.  Your usual oil filter is not particularly "fine" and lets a lot of the damaging stuff through, as in it just filters out the big bits.  There's a lot of info available, such as https://www.machinerylubrication.com/Read/29026/engine-bypass-filtration

 

I am surprised it isn't more common or well known in our country, and it does seem a sensible process for sail boats.

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Great thread. All interesting stuff. At a guess, I'm running my old buhk 20hp around 30 hours a year, tops. Changing the oil yearly would be like a trucky chanching his daily, surely?

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 I'm running my old buhk 20hp around 30 hours a year, tops. Changing the oil yearly would be like a trucky chanching his daily, surely?

Yes it would. But you will have a different potential issue. Rust! Make sure that you can start the engine once per month or so. Get the Oil running around and then sh*t off. It ensures an oil film over all metal parts to keep moist sea air off those critical parts.

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I posted this a while back as this topic pops up again.

 

No dramas about starting and engine after a long time of not running. Been a truckie here and Oz and the worst Worst WORST thing you can do is shoot down to the boat and run the engine a little to "keep it lubricated" every now and then. Just leave the dam thing! It's not going to hurt it one bit. You will soon spot those who do, look for clouds of blue smoke. One thing you should do is stuff a rag into your air intake and sump breather when laying over for a while, do it when the engine is still hot then forget about it. The engine itself will be fine. Once had a chaff cutter on the Grampians Station that had an old flathead Ford V8. Would spend 11 months under a tarp with starlings nesting in it and then would start first time off a bettery. What kills engines is not warming up fast enough under load and reving before the oil has properly lubricated, particularly turbos.

 

A foot note. Oil over time costs a lot less than rebores, rings and valve grinds so when it's getting dirty, change it. A bit of bog paper, wipe the dipstick over it and you can soon see its getting soot in it. Idling engines, particularly diesels is a killer, under running is not good either. If you need to run under full throttle run at full throttle from time to time, clears coaking on the valves. Never run your diesel for hours on the same throttle setting, will glaze the cylinders. Hope that helps?

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Never run your diesel for hours on the same throttle setting, will glaze the cylinders.

Crazyhorse I agree 100% with every thing you said, Except this one comment.

        Constant RPM will not cause glazing. It is running long periods with no load that does that. Think of all the engines that run constant RPM driving things like Gensets, Haydraulics, Pumping water, etc etc. All will clock up huge hrs with their life being all at one set RPM of Full throttle.

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It’s pretty expensive and environmentally irresponsible

Not really very expensive anymore and with Oil being recycled, hardly an environmental issue.

 

 

They don’t break down anywhere the same as older gen mineral oils and as far as the the acid build up is concerned, to make an acid you need water and to build up water in an engine don't get it up to operating temperature repeatedly.

The acids are created during combustion within the chamber itself, from the water held in the Air. It is a chemical reaction that takes place with H2O and certain chemicals that are in the Fuel and Lub oil. For instance, Sulpur used to be a common component in Diesel. When Sulphur is super heated in the combustion chamber, it produces Sulphur Trioxide. That reacts with the H2O in the air and creates Sulphuric acid. For NZ, Sulphur is now removed from Diesel, although trace amounts can still be present. Some Lube Oils can still have Sulphur in a particular form to aid with lubricating. But there are still other compnents that will produce acids as well.

 

 

getting a bypass filter installed as suggested which will remove excess water.

There are no Oil filters that will remove water from Oil. The centrifugal  "Spinners" will, but that is very expensive and a whole different ball game of filtering

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Crazyhorse I agree 100% with every thing you said, Except this one comment.

        Constant RPM will not cause glazing. It is running long periods with no load that does that. Think of all the engines that run constant RPM driving things like Gensets, Haydraulics, Pumping water, etc etc. All will clock up huge hrs with their life being all at one set RPM of Full throttle.

True, got confused it does something to the cylinders over time which from memory it scores the liners as coke builds on the rings. Most (most!) gensets etc don't run 24/7 anyway, mostly on demand. I was told change your throttle settings every few hours.

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A lot of the accepted norms from the good old days are not relevant anymore and It’s pretty expensive and environmentally irresponsible to change your boat engine oil excessively. I suspect average engine use on a yacht that’s cruised seasonally or even regularly raced during the year would not amount to much more than 50 hours, probably far less. For most yacht engines you could probably change the oil every 2-5 years or even never if you used synthetics and just did a filter change bi annually with a top up.  They don’t break down anywhere the same as older gen mineral oils and as far as the the acid build up is concerned, to make an acid you need water and to build up water in an engine don't get it up to operating temperature repeatedly. Perhaps the best way to deal with moisture apart from making sure the engine gets hot every time you use it is getting a bypass filter installed as suggested which will remove excess water.

 

Be very careful using synthetic oil. Ow (?w) is a great idea on modern automotive engines as it is basically "water" when you first start up and lubricated quickly (where most engine wear takes place) but it will start leaking out of your seals on some engines which are designed to run on standard 30 weight mineral oil. I ran synthetic in a Isuzu 2.8lt turbo and was very impressive the amount of blue smoke it blue on startup ("mate..I think ya engines phukd"). As it heats, it thickens and never had a problem but was told never put synthetic oil in yanmars. One Mack CH I drove had synthetic in it and it needed big end and crank case seals replaced. Check with your engine manufacturer first!

While on this subject, what ever happend to the "lady scott" toilet roll holders? In the 70s, a bright spark in OZ made a filter system that used drop in toilet rolls, lady scott for some reason worked best and Bellway in W.A. fitted all their trucks with them. I remember everyone in the workshop was amazed by the clean oil.

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Found this..interesting.

https://www.kc-synthetic-oil.com/toilet-paper-oil-filter.html

 

I know the Aussie made filters fitted to a Mack 500hp "super coolpower" engine did an AMAZING JOB. There were two and they held several bog rolls each and about every week we would simply unscrew the stainless steel tube, take it to bin, tip it in and put new rolls in, run the engine a few minutes then top up with oil. These primies were doing on average 2000km a week, some more.

Synthetic is certainly the way to go with automotive engines (the blue smoke should dissapear after the engine warms up and oil thickens) but NOT in most marine diesels. As I understand it, the difference is in engine heat. Some marine diesels are designed to run a lot cooler and some turbo chargers also blow their seals with synthetic oil. Going by grade is not a good idea on its own. The manufacturers know. Whitings said to me no synthetic oil for our 2GM20.

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