Yanmar 3gm30f oil loss

[sailorchic34]

Originally Posted by four winds

I'm not really on anyone's side. Just stated what Yanmar recommends.

A Yanamr GM isn't a modern design. But 5/30 and 0/30 isn't 15/40 either.

But they all displace oil lubricity with viscosity modifiers which while flowing easier at low temperatures reduces the amount of lubricity in the oil. Not having the viscosity modifiers, means there is more oil lubricity which at least, in theory, does a better job of reducing engine wear when temperatures are high enough. The use of 15-40 has more to do with straight 30wt being harder to find.

In a warm climate 30wt will provide better overall protection then 15-40.

[four winds]

Fair enough. I recall similar discussions in the 1970s regarding these issues for auto engines.

Many oils with many characteristics. Pros and cons for them all. Well stated, with the best intentions by smart members here. Complete with conclusions as to why certain choices are better.

I imagine some smart folks at Yanmar had fruitful similar discussions before changing the recommendation.


I've recently noted another change. The copper banjo washers to the newer type with the o-ring-like inner circumference. Pros and cons could be discussed. Copper seals could still be used. But neither are best if reused so that's not it. Could be Yanmar thinks the new style will yield better overall service in the long run. Maybe not, maybe just cheaper to make and the same servicabilty. Hopefully not less sevicability and the corresponding hit on their reputation. Hopefully the same applies to their oil recomendations.

Anyway, that enough out of me. Cheers all.

[Cheechako]

I think the multigrades also have something to do with engine design also. Modern tighter tolerances and modern multi grade oils have made engines in general far far better and longer lasting. Old school car engines were very worn at 100k miles. Today, that's not much at all. Having repaired many old school car engines, I can tell you this, straight 30 weight oil gums up engines very fast. Many engines I took apart had literally nearly 1/8" of black goo on everything from tappets to general intake cover troughs etc. Of course higher and higher detergent levels and engine operating temps have both helped to decrease gum up also.
I was always an old school 40w guy for diesels, but the more and more I see of engines run on multigrade oils, I think multi is the answer unless you have an old 50 designed Perkins etc.

[sailorchic34]

From Shells listing for T1 30wt oil"

It meets or exceeds API CJ-4 requirements, and is designed to provide extra performance. Shell Rotella(R) T Triple Protection(R) performs well in both older and new engines.

• Up to 22% less iron wear than Shell Rotella(R) T3 SAE 15W-40.

Ok, any modern oil will do a good job. no question. But Shell the manufacturer of both T1 and T3, says T1 will out perform T3 multi-grade oil.



Mind you, I do used 15-40 in winter. but have no issues at all about using T1 30 wt in warmer areas.

[four winds]

Wow! Sailorchic, I'm indeed surprised to see the 22% less iron wear statement. I was thinking a few % at best. And other factors of multi grade outweighing that.

Thanks for the info.

[Catalysis]

Sailorchic,
Both Rotella (R) and Chevron Delo (Isosyn) are molecularly restructured near-synthetic lubes produced with hydropressing technologies. The restructured lubes span the wider viscosity range without the need for viscosity modifiers which were necessary when lube oils were made using solvent extraction technology which took out wax and aromatics leaving a more stable base stock but which still needed viscosity stabilizers.
I would use either companies 10W-30W in a 30W application without hesitation.

[a64pilot]

Lot more to the older car engines wear and varnish / sludge formation than oil viscosity.
Almost certainly the black goo was Paraffin from using either Penzoil or Quaker State, which back in the day were Paraffin based motor oil.

However as has been stated Syn oils cannot be compared to the old "Dino" oils, as an example many Syn oils behave like multi vis oil without any modification.
Heck, even the word Synthetic is open to interpretation, there are many ways for an oil to be "Syn" some better and more expensive than others of course.

However when comparing regular oils, straight weight oil will accept more abuse and is more resistant to breakdown than multi vis oils. Its simply a matter of no free lunch, the modifiers in the multi vis oils are among the first things to break down.
Having said that I cannot believe any sailboat motor is in any danger of the oil breaking down, we just do not stress oil at all, especially if you don't have a Turbo.

I have gone to Rotella straight 30 myself from the T6 5W-40 synthetic and have reduced oil consumption. I was never bad, no smoke, but I did get a greasy stern with the T6. I used about 1 qt in 100 hours with the T6, about half that with straight 30.
I change oil at 100 hours.

[daletournier]

Originally Posted by rognvald

Fourwinds,
My engine is a 1990 3GM30F. The Yanmar shop manual and the original Pearson manual for that year recommends straight 30W for the engine, Dextron ATF for the transmission(Kanizaki) and Texaco for the heat exchanger. This is what I have used for the last 22 years. Perhaps your above submission is for a different/later model year. However, the OP should probably check with Yanmar if there are different recommendations for different model years. But, from a purely technical/mechanical basis, a multigrade oil isn't necessary in the Tropics where the ambient temperature is usually in the seventies or well-above. There are not enough temperature variations to justify a multigrade and, the OP may find with an oil/filter change with a straight grade oil, he may have less oil consumption. This is certainly a less expensive alternative than an engine rebuild or a call from the mechanic. Good luck and safe sailing.

Probably all.true but in reality it dosent matter. My last boat (3gm30f 1996) had 4500hrs on it, for the last 2500hrs I used 15w 40, it's all I could ever get. Was still running great and started instantly when i sold it 4 mths back. This was in Asia.

Sent from my vivo Y35 using Cruisers Sailing Forum mobile app

[daletournier]

One more thing, personally I think oil change frequency is more important than grade, I change oil every 100 hrs.

Sent from my vivo Y35 using Cruisers Sailing Forum mobile app

[Compass790]

This is interesting although it's for petrol engines ( gasoline )Consumer Reports:Truth Motor Oils- July 1996 I no longer stress about oil so much tho the fact I'm reading the discussion belies that!