Originally Posted by Ahoyhoy
Or, as an option to continually worrying about your need to change it because it has been a year but you only put 20 hours on it, use a proper (not cheap) full synthetic and change it every two or three years if you want to. You will find that you can also double the intervals between filter changes as well. Synthetic costs more initially, but who cares? You spend at most $15 on oil as it stands, and you have a growing concern every season's end and beginning. Put in $25 of a high end synthetic, out a sticker in it to "replace in fall of 2015" and Bob's your uncle". Use the boat as you normally would, maintaining the oil level and running it to temperature when you use it, and sleep well at night, for a lot more nights.
Just wanted to add a few more to the list so owners can decide whether or not to extend oil changes with synthetics.
[I]"10. Can I use synthetic oil in my engine?
Westerbeke does not approve or disapprove the use of synthetic oils. If synthetic oils are used, engine break-in must be performed using conventional oil. Oil change intervals must be as listed in the MAINTENANCE SCHEDULE section in the Operator's Manual and not be extended if synthetic oils are used.
NOTE: The information above supersedes all previous statements regarding synthetic oil."
"Do not leave old engine lubricating oil in the sump over the winter lay-up period. Lubricating oil and combustion deposits combine to produce harmful chemicals which can reduce the life of internal engine parts.
"My vehicle uses petroleum based motor oil. If I switch to synthetic motor oil can I extend the oil change intervals?
Toyota does not recommend extending the oil change interval. We recommend continuing to follow your vehicle's Warranty and Maintenance Guide."
Use of “synthetic engine oils” (those made with API group 3 or group 4 base stocks) is permitted subject to the same performance and viscosity limitations of petroleum (mineral) based engine oils. The same oil change intervals must
be applied to synthetic oils that are applied to petroleum (mineral) based engine oils."
BTW it was Cummins, not me, who bolded the word must.
"Q: What do you think about the use of synthetic oils in marine applications?
A: Some synthetic oils have a characteristic that enhances the useful service life of the oil, which can help lengthen oil service intervals. Caterpillar doesn’t recommend automatically extending oil change intervals for any oil, including synthetic base stock oils."
Honda Motor Company:
"Can I use synthetic oil in my Honda engine?
Honda engines are developed, tested and certified with petroleum based motor oils as a lubricant. Synthetic oils may be used; however, any motor oil used in our engines must meet all oil requirements as stated in the owner’s manual. In addition, recommended oil change intervals must be followed."
"Your Yanmar pleasure boat engine should be broken in before using the synthetic 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 possibly 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.
Director, Service Warranty and Engineering"
Please do the research for your own engines on oil change intervals or listen to the below statement, if you choose.
I wouldn't expect a company like Westerbeke to give two shits about people wanting to extend the life of their engines if it meant they had to spend money to do the research. There has been enough research done by innovative engine manufactures like Volkswagen, Mercury, Cummins, BMW, Yanmar, Volvo and the like, that it is not even an option to use mineral oils in many of them. Synthetic oil manufacturers have published the results of all their tests which show that the use of synthetic oil has only positive effects in engine longevity, oil longevity, filter longevity and the overall efficiency of the engine. I know change is scary, but so is living in the past.