[C320-list] Yanmar 3GM30F - Synthetic - why not

[sail-ability at sympatico.ca]

I am a mechanical engineer with over 40 years experience in the automotive arena. Without getting into a long diatribe on the where's and whyfore's, one can never go wrong with the manufactures recommendations for service intervals and fluid use. I've seen many cases of destroyed machinery due to owners trying to second guess; it falls under the category of " if the book says one drop, then two must be twice as good"! It doesn't work that way.

Cheers

JohnM
 
> To: C320-List at Catalina320.com
> Date: Mon, 18 Jan 2010 10:20:54 -0500
> From: wflowe3 at netscape.net
> Subject: Re: [C320-list] Yanmar 3GM30F - Synthetic - why not
> 
> 
> Not that this has anything to do with our Yanmars, but I just bought a new VW with a diesel and it comes with, and recommends using only synthetic oil. Oil changes are recommended at 10,000 mile intervals. That said, I can't see any advantage to using synthetics if it doesn't provide some measurable benefit. 
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> -----Original Message-----
> From: Pat Ireland <cherie320 at gmail.com>
> To: C320-List at catalina320.com
> Sent: Sun, Jan 17, 2010 10:41 pm
> Subject: [C320-list] Yanmar 3GM30F - Synthetic - why not
> 
> 
> All
> 
> It's about time to change oil and I suspect that synthetic oil should be a
> better oil for diesels that standard petroleum oil. But the manual
> recommends not to use synthetic oil. Does anyone know why synthetic oil
> is not recommended for a yanmar 3GM30F?
> 
> In looking for data, I found this quote on a web search. It was in a
> thread about cold starting a Yanmar 2GM20.
> 
> --------------------------------------------------------------------------------------------------------------------------------
> After receiving numerous different answers from Yanmars USA tech support
> (mostly IMHO run by local distributors who are selling *Yanmar*
> non-synthetic
> oil), I decided to write directly to Yanmar in Japan about the use of
> synthetic
> oil ...... the following is the answer I received.
> Mr. Guthrie,
> Your Yanmar pleasure boat engine should be broken in before using the
> sythetic oil. As long as you have at least 50 hours on the engine and it
> has be used at all RPMs, then synthetic oil is OK to use. Please continue
> to change it at the recommended interval for your engine as specified in
> the operator's handbook. You can expect slightly increased oil consumption
> and posibly a drip or two under the engine. Synthetic oil tends to find
> its way past gaskets and seals a little easier than petroleum based
> products. Depending on temperature, you can also use a petroleum based
> 10-30 or even a 5-20 if it is cold enough. Just be sure to use a premium
> grade oil.
> 
> Regards,
> Earl Helmer
> Director, Service Warranty and Engineering
> 
> ------------------------------------------------------------------------------------------------------------------------
> 
> Anyone have info that would dispute this information?
> 
> Pat Ireland, Cherie, 801
> 
>