Engine Oil

sailorman said:
modern engines have thin oils & are engineered to use it to get better fuel figures & emissions.
my mondeo went from semi synthetic to fully synthetic on its 2nd oil change as ford had changed the spec
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Some people do this because they consider synth oil is 'too good' and the engine won't run-in properly.
There is more to oil than viscosity, 'film strength' for one thing.
 
RichardS said:
10W-30 is quite thin for old design engines. What is the recommended viscosity for your engine? If the recommended is oil is 20W-50 or 15W-40 I would be a little concerned that the linked oil is too thin unless you are running in a very cold climate where a thin oil might be preferable.

Richard
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The vast majority of wear occurs in an engine at start-up and for the first few minutes when everything is cold and oil circulation is not established. On a worn engine the clearances are greater and a low viscosity oil is unable to prevent metal-to-metal contact, particularly in big-ends. As I have written many times I would use nothing less than 15w-40 in any marine engine and more if it is well past its best.
 
vyv_cox said:
The vast majority of wear occurs in an engine at start-up and for the first few minutes when everything is cold and oil circulation is not established. On a worn engine the clearances are greater and a low viscosity oil is unable to prevent metal-to-metal contact, particularly in big-ends. As I have written many times I would use nothing less than 15w-40 in any marine engine and more if it is well past its best.
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Just out of interest, what exactly does this stuff do - http://www.ebay.co.uk/itm/Forte-Oil-Fortifier-Petrol-and-Diesel-Engines-400ml-/191549647860?pt=LH_DefaultDomain_3&hash=item2c993fabf4
 
single said:
Just out of interest, what exactly does this stuff do - http://www.ebay.co.uk/itm/Forte-Oil-Fortifier-Petrol-and-Diesel-Engines-400ml-/191549647860?pt=LH_DefaultDomain_3&hash=item2c993fabf4
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I don't know this particular one but I have some knowledge of others. They usually contain large amounts of a boundary lubricant such as PTFE or MoS2. This makes them appear extremely good in one oil industry test, the four ball test being one of them, where the one with the miracle additive goes on indefinitely whereas the standard oil fails in a short time. What they don't tell you is that in other tests the additived one does very poorly.

The great example of this is the one where a snake oil additive was completely debunked by Briggs and Stratton, who repeated the claims that an engine would run well after the oil plus additive was drained out of the engine, whereas the one on oil only after draining stopped after a short time. In a controlled test they found that the one on oil only seized but was in OK condition, whereas the one with additive was completely wrecked. You can find this test by Googling Briggs and Stratton, well worth a read.

Another good one. When Jim Clark won Indianapolis he was driving an STP Special. During the race he spun the car but recovered and went on to win, unheard of then and pretty good today. Nobody knows what STP stands for but when asked after the race Jim said 'spinning takes practice!'
 
CAPTAIN FANTASTIC said:
I have an old Volvo MD11C; I use synthetic oil, and have been using for years; I change the oil and filter every season.
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You may be lucky cause you are doing low annual hrs but see Vyv Cox website ref engine failure due to using too high a oil spec. Still trying to get my head round this but aparently too high a TBN number causes problems. The Morris lubricants Fleet mineral Oil I have gone for has a TBN of 10.

As a charter boat my engines do circa 400 to 500hrs per year.
 
Sailfree said:
You may be lucky cause you are doing low annual hrs but see Vyv Cox website ref engine failure due to using too high a oil spec. Still trying to get my head round this but aparently too high a TBN number causes problems. The Morris lubricants Fleet mineral Oil I have gone for has a TBN of 10.

As a charter boat my engines do circa 400 to 500hrs per year.
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I am not lucky, I know what I am doing
 
CAPTAIN FANTASTIC said:
I have an old Volvo MD11C; I use synthetic oil, and have been using for years; I change the oil and filter every season.
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Difficult to understand the logic of doing so. You are paying a premium price for an oil that is intended for high speed motoring on motorways and similar heavy duties. A basic, low additive oil will do just as well without the risk of bore wear that you are taking.
 
Here in the USA I was told to use Shell Rotella 15/40, freely available in walmart, in our 3GM30F how does that fit in? previous owner said he used hypoid 80 in the gearbox but local Yanmar engineer here said use CD30 and he gave me some for top ups after he changed ithe oil on service.
 
Robin said:
Here in the USA I was told to use Shell Rotella 15/40, freely available in walmart, in our 3GM30F how does that fit in?
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It is a 15w 40 oil to API spec CJ4 witha TBN of 10.1 so it probably fits in as one of the oils with an unnecessarily high spec and the sort of TBN that Vyv advises against


previous owner said he used hypoid 80 in the gearbox but local Yanmar engineer here said use CD30 and he gave me some for top ups after he changed ithe oil on service.
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The viscosity scales for gear oils are different to those for engine oils such that an SAE 80 gear oil is about the same viscosity as an SAE 30 engine oil. The EP (Hypoid) properties are not needed but without knowing the details of the gearbox construction its not possible to say if it would be undesirable or not. Probably not
 
VicS said:
It is a 15w 40 oil to API spec CJ4 witha TBN of 10.1 so it probably fits in as one of the oils with an unnecessarily high spec and the sort of TBN that Vyv advises against

Thanks Vic. Next time we do an oil change we will try and find something else, but so far we have only done 2 hours since the service and oil changend I'm not even sure what options there are over here. The engineer found some straight 30 in his workshop enough for the gearbox but not enough forthe engine. Maybe if I look around the agricultural/farm stores I might find something, I think a lot of ride on lawnmowers here have Yanmars.




The viscosity scales for gear oils are different to those for engine oils such that an SAE 80 gear oil is about the same viscosity as an SAE 30 engine oil. The EP (Hypoid) properties are not needed but without knowing the details of the gearbox construction its not possible to say if it would be undesirable or not. Probably not
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Just to add to my last post our engine only has 1250 hrs on from new in 1998 so it is not an 'old' engine but may perhaps be considered an 'old design' We don't have a problem with startups in cold conditions either as around here 70F is considered to be cold and the least we see on early mornings in midwinter would be 55F and by the time we might get to the boat and start it up it would most likely be mid 60s F, like mid -summer in the UK.

It is beginning to seem like we need to replace our boat engines annually just to keep pace with oils technology not the other way round:disgust:.
 
vyv_cox said:
Difficult to understand the logic of doing so. You are paying a premium price for an oil that is intended for high speed motoring on motorways and similar heavy duties. A basic, low additive oil will do just as well without the risk of bore wear that you are taking.
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The key advantage in using a top quality semi-synthetic or synthetic oil is that you can safely extend the oil change interval. However, as the Captain changes the oil every year anyway, I'm also at a bit of a loss. :confused:

Richard
 
RichardS said:
The key advantage in using a top quality semi-synthetic or synthetic oil is that you can safely extend the oil change interval. However, as the Captain changes the oil every year anyway, I'm also at a bit of a loss. :confused:

Richard
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Mineral/conventional oils break down under pressure and temperature and their chemical composition changes with time much faster than synthetic oils. Also, synthetic oils have additives to remove deposit compounds. The oil molecules of mineral oils is larger in size which helps to "bridge" the gaps between moving metal, however, although the synthetic oil molecules are smaller, they do not break down and maintain lubricating ability under wider conditions. Some will argue that the additive detergents encourage carbon particulates to contaminate the oil, however, it has not been demonstrated in practice. Oils (mineral) in the 70's were very poor in comparison to synthetic oils, breaking down easily, causing huge problems with aero piston engines, being air cooled were operating at higher temperatures. We can not expect manufactures of older engines/models to review and subsequently to change the oil specification and I dont suggest that others should use synthetic oils for their older engines. The reason I change oil is because older engines will contaminate the oil much quicker due to larger clearances between pistons and cylinder, hence diluting the oil with small amounts of diesel, also the cost is very small, as synthetic oils are the same price as good mineral oils. In additional, a cold engine with synthetic oil will start easier, with less strain. And again, I dont suggest that older engines should use synthetic oil, I simply explain why I use synthetic oil on my old engine.
 
VicS said:
It is a 15w 40 oil to API spec CJ4 witha TBN of 10.1 so it probably fits in as one of the oils with an unnecessarily high spec and the sort of TBN that Vyv advises against
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Vic,

I contacted the Morris lubricant tech dept and the problem as I see it is that you cant buy 15W40 mineral oils to CD spec which I believe dates back to the 80's. As soon as the spec goes up through the letters CF, CH Cl etc the TBN number increases. I got the impression that while a lower number than 10 would be preferable its better than most modern oils where its even higher.

I ended up buying Morris Lubricants CDX Fleet mineral oil 15W40 where at least it has a data sheet that shows a TBN of 10. I am not sure you can get the TBN of many supermarket oils.
 
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