Hello, I have an SM200 with the Yanmar 4JH3 engine having about
2000HRS. To increase the oil change intervals, I have envisaged the use
of Synthetic lubricant. Any experience in using synthetic oil?

I attended a 3-day diesel workshop sponsored by Yanmar. I worked on,
assembled, and disassembled a 4JH3-HTE for 3 days. The class
consisted of 12 folks, but I was the only one who owned a 4JH3-HTE so
I received 1 on 1 time.

It is easy to get confused on this issue because Yanmar makes some
engines that use synthetic oil, but not the 4JH3-HTE.

According to the Yanmar instructor, Yanmar reccomends against use of
synthetic oil in the 4JH3-HTE. I believe it has something to do with
the Turbo, but not 100% sure. He said that if you use synthetic oil
in your Yanmar during the warranty period this will void the warranty.
You are probably out of the warranty period, but with Yanmar's
position on this issue, I would advise caution. I think I will listen
to Yanmar on this issue because the downside is just not worth the
upside...

Regards,

Bill Rouse
s/v BeBe SM2 #387
anchored Opua, New Zealand