Synthetic oil for diesel/transmissions

[never monday]

While Microships engine would be a good candidate for synthetics. I think converting at this time would cause the leaks to start.

[never monday]

Please don't take my opinions as anti synthetic, I'm not.

I believe there is a correct application for synthetic and many more incorrect applications.
If you have a new/rebuilt 0 time engine break it in for 250-500 hrs on dino oil then go synthetic.
The extended break in is because our diesels run slower than a gas engine. It takes more time to properly wear in the cylinders.

P.S. I still run dino oil in my 6L Cummins in my truck. It has 125K on it in just over 2 years.

[Microship]

Maybe for the moment, since the boat is new to me, I should take the "if it works, don't mess with it" approach... and over time get educated about the options and the engine's behavior.

Thanks folks!
Steve

[cburger]

Foley Engine in Mass. has some very good info regarding the synthetic oil issue for motors as well as reduction gears.
Foley Industrial Engines, marine engines, engine rebuild kits, marine rebuild kits, marine engine parts, replacement engines, rebuilt marine engines, wisconsin engine parts, continental engines, perkins engines parts, perkins diesel engines, zenith c

[MidLandOne]

Just talking small sailboat auxiliaries here (not talking big powerboat engines, whether pleasure or commercially rated, where one should just follow the engine manufacturer's recommendations for all fluids - this is always easy to due to the much larger bulk quantities to be purchased).

A few years ago I discussed engine oils for these with my favourite oil manufacturer's technical people both with respect to synthetic oils and also for the cases where the engine manufacturer specifies single grade oils. Their recommendation, regardless of whether a multi or single grade was specified by the engine manufacturer, was to just use whatever the oil company's current high volume product was on the shelf for diesel engined passenger road vehicles. Said that is always the best choice including for ease of purchase. I suspect that they are correct and have followed that in my own case.

For gearbox, for first fill I buy the box spare part oil to determine what it is if they do not otherwise fully specify the oil. From then on I just buy the equivalent from my favorite oil manufacturer, although often minimum pack quantity is 4 litre - enough for 4 or 5 refills for many small boxes. In my current case oil turned out to be a multigrade synthetic gear oil and that is what I use.

I make a habit of running the engine, well loaded, for at least an hour at least every 2 weeks all year round, and suspect that has more value than fussing about oil choice.

[Ex-Calif]

Originally Posted by never monday

While Microships engine would be a good candidate for synthetics. I think converting at this time would cause the leaks to start.

Anecdotally, I agree with this completely. In my 30 years of busting knuckles I have come across many cases where something was added, changed, modified on a "mature" engine and then the fun started.

Of course the successes you never hear about but...

Seals, joints, etc. etc. take a set and are happily going along in one set of "chemical" circumstances. You change the oil compound or disturb a system and all of a sudden you start getting problems.

This could just be old mechanic superstition but for engine crankcases I would switch to synthetics very early after overhaul or leave it alone.

For gearboxes the arguments are a little more compelling as the oils are definitely not working as hard as in the crankcase. You also don't have all the combustion gas by products mixing in etc. etc.

For long life, equal or better lubricity and improved temperature management I like synthetics for gearboxes.