Synthetic Engine Oil

Just the opposite. The reason that synthetic lubricants have been developed is that the base oil does not break down so readily in very hot engines, i.e. high performance, turbo-charged engines used intensively. The additive package that is in these lubricants is aimed at the same type of duty.

Using high performance lubricants in a low performance engine can cause wear problems because the temperatures needed to make the additives work correctly are never reached.

If you check your engine's manual it will specify the type of oil to use, API CC or CD being quite common for Volvos, Yanmars, Bukhs and others. The synthetics will have grades more like API CG, CI or perhaps even more.

So unless your engine is a turbo-charged mobo running flat out for hours on end, it will prefer a standard mineral oil.

This link gives Shell's lubricant range for diesel applications.
 
If you look at oils in garages, there are some which are for the "older type of engine". This means that the piston clearances, rings etc are less accurate than modern engines, which can use synthetic oils which tend to be more viscous. If you put synthetic oil into an "old " engine even if it has never been used the oil consumption will be dramatic because the oil will burn off because the tolerances are all wrong. You may get away with semi synthetic, but I strongly recommend that you stick to the makers recommended lubricants
 
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Oooooh!!! A Gardner!!!! A proper engine.
Used to own an 8 wheeler with one in - pig to drive but a wonderful engine - seemed capable of going on for ever.

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The main engine in my fishing vessel is a Gardner, well over 60 years old and still all original. Best thing that ever came out of Britain. I use mono grade mineral diesel 40. I also use the same oil in the Kubota auxillary which is relatively new at about 12,000 hours. The Gardners are meant to leak oil, there is a distinct lack of gaskets about the engine.

I drive a Porsche 928s and have used synthetic oil in that but have now reverted to quality mineral oil. We have a very popular Porsche forum where at the moment we have the oil discussion. It seems that here and in America 928 engines that run on synthetic are suffering from cam lobe wear. The synthetic oil is a much better spec oil but apparently lacks the correct additives that the older style oil has in most cases, zinc.

Synthetic oil in gearboxes and diffs seems to be a good choice though.

I would recommend using the manufacturers advice and also if possible use mono grade oil.
 
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Used to own an 8 wheeler with one in

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Bet you would have refered to it as an 'eight legger' to the lads when you operated it? /forums/images/graemlins/wink.gif
 
There have been discussions on some motorcycle websites too. Among the modern bikes the question is 'which synthetic?', but some classic riders want to inhale castrol R and do frequent rebuilds. I'm surprised by the Porsche cam thing, if synthetic can stop a desmo Ducati wearing out, I would have thought it proven to be good. Is it to do with the low cold viscosity of synths?
The most coherent argument against synth in boat engines is glazing of bores under light loads. And of course the cost, because it still gets dirty and wants changing twice a year, even when you've only been to Cowes twice. I think buying a decent make is as important as the type.
Bring back Nigel!
 
If you use a quality synthetic of the proper viscosity and API grade, you won't have any problems using it in any engine. Synthetic doesn't break down like petroleum oils, so you can generally go longer between oil changes. Use a high-quality oil filter. I wouldn't use semi-syn as it doesn't give you an extension on oil-changes, it just costs more. On top of that, you generally don't see a percentage listed on a can of semi-syn - a couple drops of synthetic in a can of bog-standard oil, and it's called semi-synthetic and priced at a premium. http://www.amsoil.com/powersports/marine.aspx
 
<<< If you use a quality synthetic of the proper viscosity and API grade, you won't have any problems using it in any engine >>>

Sorry, this is totally untrue. Synthetic lubricants have an additive package that provides a high Total Base Number (TBN) to combat the acids produced by combustion. The oils quoted in the link you provide have a TBN of 12, which is fine for high powered engines, or heavy duty applications, as quoted. Shell Rimula X, intended for extreme duties, has a TBN as high as 16.

The oils specified for low power duties such as yacht auxiliary engines require a TBN of about 3-4. This would be typical for an oil to API CD. An API CC oil that I am very familiar with was developed specifically for single cylinder Bukh engines in lifeboats. It had a TBN of 2.

Using a high TBN in low powered engines will undoubtedly cause wear, not only in the bores but also, as noted above, to cams and tappets. This is nothing to do with bore glazing, which has a totally different cause.
 
Not that you need any support in your argument, Vyv, but to add to what you have said, an independent marine engineer once told me (I was trying to buy 'best quality' oil from him) he makes more money out of people who have used expensive oils in their engines than almost any other failure. The failure being glazed bores.

The second most common failure is people loving their engines too much, not enough revs! He went on to point out that most marine engines are small plant engines, made to be run all day flat out!

I always buy Shell X100 a basic 10 - 40 mineral oil.
 
Had an oil problem with a new Yanmar that polished its bores. Did quite a bit of digging including speaking to Castrol oils tech dept, and they were adamant that a fully synthetic oil in an old design engine tthat wasnt built for it was a recipe for problems. I cant now remember the exact reason why, but it was something to do with the additives and caused polishing. Yanmar tecnical agreed with this.

Certainly the bores in this Yanmar were absolute mirror finish when I took it apart. Note - this was not old fashioned bore glazing (which I believe is more about a varnish typoe deposit filling up all the micro grooves which should hold oil) but a lubrication breakdown causing burnishing.

And that was the other interesting thing - the Yanmar (a 2gm) was described as very much old technology - not something you think of with the Japs.
 
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old technology - not something you think of with the Japs.

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I think you will find that the Japs have needed cement mixer engines since about 1940 something! /forums/images/graemlins/grin.gif
 
I allways use sythetic in my Gardeners,no problem,they dont use or burn any oil and they are circa 1953 so they have done a lot of hours,i have 4,single cylinder unit L2`s,running generators and 2 four cylinder 4lw running air compressors ,they are like new. i change the oil every 200 hours,and clean the gauze filters which are allways spotless.
 
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