Synthetic oil any advantage?

[Guest]

Is synthetic oil any better than normal for engines that spend a lot of time stood still?

Bernie

 

[DepSol]

Synthetic best for performance engines and you will lose more oil than normal.

Dom


My boats going back in the water ;-)

 

[Guest]

I have been told by my engineer, that if you have an engine that is not " a spring chicken" you should avoid fancy oil. apparently, it has such strong detergents that it will clean up the inside of your a treat. In an old motor this could well lead to failed bearings etc.

My current 13 year old Volvo thrives on the cheapest stuff Tesco has to offer. Rejoice, you don't have to buy the dear brand.

 

[tome]

I've talked to Volvo who have said that, yes you can use synthetic, but that you won't be able to go back to ordinary oil.

I never bothered!

 

[gtmoore]

It makes you wonder about these oils that apparently provide good protection during startup though. The Castrol Magnatec that I use in my car is supposed to provide a certain amount of protection to the engine's components during the startup procedure by "clinging" to the parts and protecting them before the oil gets a chance to circulate. The usage of an engine in an average boat is probably punctuated by at least 5 days of inaction and I would have thought that it would have benefited from this kind of oil.

Unfortunately, the Beta engine I have in my boat specified a different viscosity rating to the Magnatec diesel oil they had in Halfords so I had to go for the normal Castrol diesel oil cos I don't know if this would have caused a problem. Probably not but I would have kicked myself if it had!

 

[ccscott49]

Totally agree with Dom, I've used high grade synthetics in racing engines, due to it's better lubricity at higher temps, but for a boat diesel, use what the army uses for all diesel engines, that often sit for months at a time, good quality, standard diesel engine oil. Which will cling to the components, if you haven't started the engine for a while, turn it over on the stater, with the fule stop lever in the stop position, or the solenoid disconnected, until it has had time to pump some oil around, then start it. Some very exotic engines (Lambo), used to have an electric pump, to prime the system, before it would allow the starter to be engaged. This procedure is very common with engines that sit for long periods. Just a suggestion, but I use this procedure when I've been away from the boat working for over a month.

 

[oldharry]

Synthetics are fine for high performance high power engines such as you may find in modern cars, or in highly strung turbo-charged plastic bathtubs.

Yer average yot engine just doesnt need it, and its a waste of money to put it in a slow running boat engine. And the additives may actually do harm as it doesnt run hot enough anyway.

Very few yacht diesels ever get anywhere near wearing out and are usually repaced because of corrosion damage to injectors and engine externals making repair uneconomic, or undesireable.

 

[vyv_cox]

Use an SAE CD oil for any normally-aspirated diesel engine. This grade is recommended for Bukh and Yanmar that I know of, and probably most others. Lubricants with a higher rating, SAE CF, CG or higher, have a much higher base number to cope with the increased oxidation potential of turbo-charged, high power engines. Use of these high base number oils in a low power engine will give increased bore wear and glazing, especially during battery charging.

Fortunately the CD grades are cheaper and tend to be sold in car parts shops, Halfords, etc.

The main advantage of synthetics is that the hydrocarbon chain length is much more strictly controlled than in a natural oil. This reduces sludging and staining in a "hot" engine, plus giving more stable lubricant film thickness and other properties, but is of no value whatsoever in a yacht engine.