Synthetic lubrication

wingsofraven · Member

Synthetic lubrication

Farron · Senior Member

Hello Frank,

Kubota specifically recommends against synthetic oil for use in their diesel engines.

One of the main advantages for using synthetic oil is an extended oil change interval. This is a bad idea with a diesel engine application as scheduled oil changes are critical to removing dirt and contamination from the lube oil system.

There are many different types and brands of marine transmissions that use various types of oil.

For transmissions, we recommend that you use the type of oil recommended by the transmission manufacturer.

-- Edited by Farron on Friday 12th of February 2016 08:53:55 AM

Blue Moon · Veteran Member

My Beta 38 has just been installed and so I'm now planning for parts and maintenance. I'd like to hear some more specifics about synthetic oil use in these Kubota engines. To be clear, I am NOT talking about extending service or oil change intervals, but only about maximally protecting and minimizing wear in the engine over the typical range of marine use.

My work is very involved with vehicle and engine manufacturers, lubricant companies, and test laboratories. 100% consistent feedback from all is superiority of synthetic oil (though even the definition of "synthetic" can be troublesome. Recently, due to very inconsistent testing and monitoring of compliance to API rating standards, the dexos certification, with rigorous formulation and testing requirements, has been established by GM and been adopted by all significant, reputable oil companies. Substantially all of the oils compliant with the newest, toughest dexos2 standard are synthetic.

My Beta Marine Operators Maintenance Manual calls out:

Engine oil: Engine oil quality should have the minimum properties of the American Petroleum Institute API classification CF (CD and CE have been superseded by CF). A good quality SAE 15W/40 mineral based multigrade oil as used in most car diesel engines will meet requirements. An acceptable alternative are mineral based lubricating oils that are sometimes called semi-synthetic (or synthetic blends) and are blends of mineral oil with no more than 30% synthetic oil.

and

Note: Do not use lubricant additives, and we do not recommended totally synthetic oil.

There is lots of internet chatter about use of synthetic oil in Kubota engines, mostly related to agricultural equipment, including a bunch of relayed feedback from Kubota dealers, company warranty administrators, and so on, saying that use of fully synthetic oil is fine so long as it meets or exceeds the requirements of the API CF certification (note: the latest API certification for diesel engine oil is CK). I fully recognize that not all internet information is reliable, but if even 10% of it is accurate, theres a legitimate question here.

So why, specifically, does Beta Marine/Kubota state that the latest, dexos, better-than API, synthetic oil judged superior by just about every expert in internal combustion engines should not be used in these engines? Some of the new Shell Helix and Mobil 1 oils are amazing.

Stanley · Guru

Kubota cannot test every lubricant available so they recommend what they know works and keeps these diesels running, often for many more hours than any competitors engines, even in extremely harsh enviroments such as small back hoes, diggers and tractors. We do recommend mineral oils that work well but we also have a number of customers who use synthetic oils without any ill effects so if your choice is to buy synthetic oil, that is fine, as long as the synthetic oil meets with the classification standards as recommended by Kubota.

Here is a copy from the Kubota Engine corporation FAQ page on their website;

Q: I can't find diesel-rated 10W30. Can I use 15W40?

A: Yes, many of our customers use 15W40 engine oil in their Kubota diesels. Just make sure whatever oil you use has an API rating of CF or higher.

Can I use synthetic oil in my Kubota engine?

A: Kubota recommends oil with an API rating of CF or higher. If the synthetic oil meets those standards, it can be used in Kubota engines.

Q: If I use synthetic oil, can I extend my oil change interval?

A: No. Since Kubota can not test every type of synthetic oil, we can not predict how long it will last in the engine. So the oil change interval must remain the same.

-- Edited by Stanley on Friday 24th of February 2017 03:30:20 PM