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Synthetic Oils


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Considering that

 

a) there are lots of people out there who advise against it

 

B) small marine diesels don't need it

 

c) it's more expensive than your usual oil

 

why would you bother?

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You have to be very careful about synthetics. Many are not good oils at all. There is more to oil than just being slippery. Diesels are particularly vulnerable to syth oils. Many of the makers of these oils are trying to just make something as slippery as possible. But in a diesel, that can be death.

Good syth oils are a package. They are about stability, anticorrosion, heat dissipation, Acid neutralisation, cleaning and holding the carbon and metal particles in suspension to get it to the filter.

Don't get fooled by the wide range of numbers, like the 0-40W. Penzoil have one that is 0-60. But most Diesels will burn it as fast as it burns the fuel. the multigrades have nothing to do with viscosity inside the engine. It is a relation to the freezing point of oil. So in reality, the lower the viscosity number, the colder the climate you operate in.

Oil packages are not designed by oil companies. The oil producing company makes the base stock of oil. The engine manufacturer designs and engine to do a particular job, which means the engine will be subject to specific conditions. So they design to tolerences and may use special materials. They then determin what they need as an oil package to make the engine perform and last for the time they expect. They take the requirements to the oil producing company and say we want an oil that meets this specification and the oil maker adds an additive package to bring their base stock to that requirement.

Sorry about this being long winded, but to wind up, bascialy the engine manufacturer states that oild type is best suited for their engine and at what operating temperature and thus it is best to stick to that.

 

I use Amzoil products. Very expensive, but pretty amazing stuff. I found that it was not economical to use it in the Perkins engine. It just goes through to much oil in this specific engine. I have used it in many other engines and it has been worthwhile. It can save fuel, reduce heat and the big No 1 reason I use it is because of the very high milages I normally do. If you don't clock big K's, it isn't isn't worth it. You need to be looking at 30K Kms/yr minimum to make it worthwhile. I was doing oil changes every 4 weeks with ordinary oil and being able to extend to a year was where the saving came in. But you still have to change the filters and they have to be very good filters.

I continue to use it in the Boat gearbox though. The main reason is the protection it can give should the gearbox oil cooler fail and salt water enters the box. It has dropped the box temp dramatically and heat is death to a hydraulic box.

 

Once you glaze the bores of a diesel, it is often a rebiuld. Sometimes you can bring them back from the edge, it just depends on how bad it was. The biggest killer of a Diesel is treating it kindly.

NEVER warm a diesel by idling it in nuetral. You must get it into gear and get some revs on and let it warm underload, or if you are heading out, just drop the lines and go. Don't wait till it warms up. If you tend to run the engine at low revs most of the time, then every now and then open her up and work it hard.

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Right on Wheels. Thrash that diesel. They HATE idling. I found out the hard way.

We wintered over in Corfu Greece one year. The Marina charges for electricity were quite high, so we used to charge the batteries with the motor, a Volvo MD7A.

There was a lovely 85 ft S&S stink boat next door that was easily the best maintained boat I had ever seen. Had a perminant live on board skipper/engineer and deckhand. This guy used to make VW racing motors in california and was a mechanical genius. The owner of the boat (was called "Resolute") recognised the guy's ability and hired him as engineer, then skipper when the skipper quit.

Anyway, this guy used to wander past the boat, and saw me charging the batteries at about 1/3 throttle, and advised me that it would stuff my engine in short notice. Being about 25 and knowing EVERYTHING I told him to f*ck off, which he did.

About a month later I turned the key and all it did was turn.. No compression. The rings were carboned solid into the grooves and the valves had all partially burnt out with massive carbon deposits on them.

Sam, the superyacht skipper, to his credit, helped me pull the engine out using the boom and mainsheet. We got oversize pistons, re-ground the valves, got the block rebored, and put it all back together. At the same time we ditched the down the dipstick oil pump and plumbed in a perminant oil change pump to the low point of the sump.. Never forgot that guy's kindness and help, or the lessons he taught me:

1. ALWAYS change the oil on time.

2. ALWAYS operate a diesel under load.

3. Fit the biggest strainer and best diesel filter you can in a place that is really EASY to access..

 

He was right on all counts.

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Sorry about the thread drift wet dream....

 

As a postscript to the above story, we were anchored in Port Fitzroy some 12 years later when I saw a familiar profile. It was Resolute!

It had been re-named by the new French owners, kept in Noumea, and had just had a refit in the Naval Dockyards.

I went on board, and sure enough, same boat. Small world...

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Good on ya Smithy.

Yep changing oil often is the key. Regular oil changing with a good quality Diesel Engine oil can be better than using an expensive Synth. Ofcourse there are cheap Oils that I would never consider using, like the elcheapo Repco brand etc. You need to read the back label on the container. The key is the specification that the oil meets. Although you have to know what some of that means.

Now, in saying all that. The larger high speed Diesels, like the bigger yanmars and Mitsis etc can benifit from a good synth oil. But be prepared to spend $200 or more to fill it up. And you really want to change it yearly anyway, so as moisture biuld up can be removed. So if you change your oil at a yearly interval anyway (you don't clock many hrs a year) then it is hardly worth wasting $200 against say $50.

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A LOT of info!! Thanks guys! To earn enough to keep this "I want to sail away into the sunset..." dream going, I am a truckie (B trains etc) and i know a lot have gone away from mineral oils. The benifit of synth is its low viscosity on start up (so it lubes the engine quickly) and its low acidic (SULPHUR) content. I know most truck engines are direct injection (yanmar has recessed pistons and expansion chambers) but so do a lot of current small jap turbo diesels that also use syth oil. So why not Yanmar? Glazing from what I understand is from improperly burnt fuel (excessive idling) from no load conditions. NOT from the lubricating oil?

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One advantage of synth oils is that they don't tend to change viscosity with temp so much. One of the biggest advantages is the ability to maintain a flim on metal (when engine is shut down) that can stay there for months protecting the internal engine parts from corrosion and being there when you start a cold engine. (although the add that states 75% of engine wear occurs at start up is more a Tui add). The only part that wears that badly at start up is the starter motor.

Synthetic oils can be a problem because the boat engines don't get very hot. High speed diesels like the yanmar are not so bad. But the little baby Yanmars don't get very hot at all so you do need to be careful with what you put into them.

Amzoil have a very specific Marine Diesel oil that is formulated for just these issues. I highly recomend it. Once you use it, you will probably never do the hrs to need worrying about replacing it and that is one of the really big advantages of using it. In Vehicles, you can easily achieve 50,00Kms between replacment. Some people will go to 100,000Kms. A friend of mine changes his religously at 25,000Kms. But you need to use a good quality filter. Donaldson make the Amsoil filters.

Oil shouldn't have sulphur in it, but that is not what causes Acid anyway. Acid comes form the Sulfher in the fuel. Of course we don't have sulpher in Fuel now anyway.But when we did, for every 10ltrs of fuel burn't, we would get ruffly 1ltr of water and 1/10th of a ltr of Sulphuric Acid. Part of the Additive package put in oil is a Zinc compund used to nuetralise Acid.

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Spoke to the Yanmar agents who do repairs at Half Moon Bay (since I have now moved my "money black hole" up to the Tamaki) and they said go for it! In his opinion synth oil is a better choice than mineral... hmmmm ... now I am TOTALLY confused!

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Just weigh it up against Cost WD. As liong as you get a proper, or I should say a known brand name Synth oil and not simply an additive or a Sumgsong synth from Supercheap, you will be fine. But you have to weigh up the cost. If it is hard to do changes and you want to extend the change time, then it can be worth spending the extra dollars.

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Actually what has changed my mind on this is the condition of the current (mineral) oil. The engine hasn't done that many hours since the last change but enough that it should look pretty messed up!!! and still looks great! I don't think its worth the risk and agree with you Wheels to stick to whats working. The engine even after weeks of non-use doesn't blow smoke on start up so staying well within the intervals of oil changes would probably just as good as changing to synthetic. Yanmar still hasn't come up with a "own brand" synth so they must know something that makes synth oil not a great idea? :?

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