Shell Rotella T6 5W-40 Full Synthetic Diesel for Yanmar 3GM30F

[Tenedos]

Ahoy sailors,

Hopefully a simple question for those who know what this is all about. I am about to change oil for my 3GM30F Yanmar and was looking in what to use. I am not sure what all those numbers mean on oils

Is Rotella T6 5W-40 Full Synthetic Diesel good for it? I read in the forums that full synthetic might be an overkill for old engines but I don't mind an overkill as long as it doesn't hurt the engine.

I would rather go with a robust oil and pay a bit extra than have doubts.

Any recommendations?

P.S. If it matters at all, boat is in San Francisco Bay.

[fryewe]

That oil would be fine, but non-synthetic Rotella T 15W-40 is great oil at lower cost. I have used it in my Yanmar engines for over 30 years...and my original 41 yo Yanmar is still running fine on it.

[jimbunyard]

If the engine was broken in with full synthetic go for it. If not, or if you don't know, best to stick with regular 15W-40 Rotella. I doubt you're trying to meet any EPA mileage requirements...

[Tenedos]

Originally Posted by jimbunyard

If the engine was broken in with full synthetic go for it. If not, or if you don't know, best to stick with regular 15W-40 Rotella. I doubt you're trying to meet any EPA mileage requirements...

Thanks Jim. I don't know if there was synthetic oil in before but I doubt it. I believe you are not supposed to go from synthetic to regular though?

[Sandero]

Originally Posted by fryewe

That oil would be fine, but non-synthetic Rotella T 15W-40 is great oil at lower cost. I have used it in my Yanmar engines for over 30 years...and my original 41 yo Yanmar is still running fine on it.

If you can believe this... and it's seems totally weird... but I found a full 5 gallon pail of it... unopened... right in front of my apartment building. WTF??????????

It was like a gift from the heavens.. exactly what I use!

[Calif.Ted]

Shell Rotella and Chevron Delos have been the preferred oils for diesels for decades, I find that straight 30 wt. works fine in our non-freezing not very hot climate.
My 320 is an '02 I brought down to San Diego from San Francisco about 6 years ago.

[HBWT]

As said before, do not use synthetic unless engine has been run full synthetic since break-in. Multigrade 5w-40 rotella is what Yanmar recommends for non turbo models. Strait grade only for everything with a Turbo.

[Tenedos]

Thanks everyone. I ordered a 15W-40. Will change next week.

[Laser fun]

While you're out shopping for Rotella T, see if you can figure out the difference between Rotella T and T4. Shell's website indicates T4 meets newest API standard and I've got an idea that T4 is replacing T on the shelves but no ironclad proof yet. We've still got a gallon or so of T left for our 3GM30F which seems to take about 3 quarts using an extractor thru the dipstick port and changing the filter!

[Caliber40]

Just curious guys. You who suggest don't go synthetic if motor wasn't broken in with it. Why not? I can find no correlating info on this subject on any web site.

Synthetic had been proven in test after test the superior lubricant. If I had the choice I'd use synthetic every time.

Greg
SV Ti Amo

[TommmD]

The warning not to switch fr syn to conventional has been around since syn came out. It's personal preference as far as I can tell. I've switched well run multiple car & boat engines to syn w/ no Ill effects. Yes it's more money. But in the context of overall cost of ownership, not much. In a perfect world, it really isn't necessary. I share the world I live in with Murphy however, so a little extra heat resistance is worth it to me. Of course, Im probably the only one who's ever heard his temp alarm go off..

[evm1024]

Originally Posted by Tenedos

Thanks everyone. I ordered a 15W-40. Will change next week.

Get a hold of Blackstone and send them a sample of the old oil. They will test it and tell you what type of oil (Dino or synth) and tell you what metals etc are in the oil.

This will establish a baseline on the condition of the engine.

Blackstone Labs



Just a happy customer....

[evm1024]

One more thought Rotella and Delo are intended for diesel engines specifically. Best to stay with an oil designed for Diesels.

Diesel Engine Lubricating Oil
^.......^........^.............^

[jimbunyard]

Originally Posted by Caliber40

Just curious guys. You who suggest don't go synthetic if motor wasn't broken in with it. Why not? I can find no correlating info on this subject on any web site.

Synthetic had been proven in test after test the superior lubricant. If I had the choice I'd use synthetic every time.

Greg
SV Ti Amo

Because you didn't look very hard?

From the fifth listing on the first page of a google search. It's just a magazine article so you're on your own in trusting it's veracity.

"Synthetic oils may not be ideal for a vehicle that has high mileage (engine hours) and has only used mineral base oils during its lifespan. If you were to change the oil to a synthetic in this type of vehicle, it could lead to a number of problems. The oil’s natural detergent action could wash off varnish and other soot deposits that are sometimes left behind with certain mineral oils. This action of cleaning deposits off cylinder walls not only can cause the engine to use more oil but also can reduce cylinder wall thickness and allow small amounts of oil to bypass the piston rings and burn up in the cylinder head."

When to Choose a Synthetic Lubricant

I tend to trust, and recommend, what has worked for me in the past, and is working for me now. I use 20W-50 in my gas engines and 15W40 in diesels. I hear way too many rattly-ass-top-and/or-bottom-end-on-startup 'modern' engines to have much faith in 5w-20 oil, but hey, to each his own...

[bcboomer]

I was in the service end of business for 40 odd years and heard this warning a lot. The only time I saw a problem was a gas engine that hadn't had an oil change in at lease 30,000 miles. The high detergents in the synthetic pulled all the sludge up from the pan and plugged up the oil galleries with "interesting" results.
If the engine oil system is in reasonable condition I'd only use the synthetic if it was the same price. Synthetic really only has 1 advantage. It stays thinner at cold temperatures so you get faster lubrication on start up. Really only important at well below freezing.