Monograde Engine Oils

The manual for my older Yanmar recommends, for my temperatures, mono grade SEA 20 oil. This is hard to find at least for me in remote Alaska. I have been using Delo 400 15-30. I fine lots of conflicting info on the web concerning this but what do you think? Is it worth seeking out a mono grade oil? I know Delo 400 makes a monograde SEA 20 oil but I have not located a source.

It's hard to argue against the folks who designed and built the motor. I'd try and use what they recommend.

Ken

How old is your engine? Mine is 40+ (not a Yanmar in any way) and the recommendation from the manual is SAE 10, 20 or 30 depending of temperature or 15w40.

L

Are you sure it only recommends SAE 20? My Perkins, Kubota, and Westerbeke manuals recommend SAE 20 OR 10W30. Nothing wrong with 10W30 changed at normal recommended intervals, especially in cold climates.

This is the oversimplified, short story.

Engines with no oil pumps and no oil filters used straight weight, non-detergent oil. When pumps were used, multi-grade oil made cavitation less likely. When filters were used, detergents kept impurities floating long enough to trap them in the filter. Engine protection was based on viscosity until additives and synthetics offered other protections.

Lou, if 15-40 is a mfr. approved oil, why not use it. Lots of engines do, and it`s readily available.

BruceK said:

Lou, if 15-40 is a mfr. approved oil, why not use it. Lots of engines do, and it`s readily available.

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Well sae 30 is mentioned as first choice for my climate and I have easy access to it so the choice.

L

Boat said:

This is the oversimplified, short story.

Engines with no oil pumps and no oil filters used straight weight, non-detergent oil. When pumps were used, multi-grade oil made cavitation less likely. When filters were used, detergents kept impurities floating long enough to trap them in the filter. Engine protection was based on viscosity until additives and synthetics offered other protections.

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My Lehman manual recommends straight wt. oil, it has a pump and a filter.

When you find the correct oil to the engine mfg. specks . simply purchase enough for a number of oil changes.

The engine builder knows what is required .

Single weight oil comes in many detergent grades ( CC, CD ,CF etc) the engine builder knows best what is required.

Boat said:

This is the oversimplified, short story.

Engines with no oil pumps and no oil filters used straight weight, non-detergent oil. When pumps were used, multi-grade oil made cavitation less likely. When filters were used, detergents kept impurities floating long enough to trap them in the filter. Engine protection was based on viscosity until additives and synthetics offered other protections.

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The only engines I've seen without a pump and/or filter are on lawn mowers and small portable generators. Basically engines under about 10hp.


Also, the issues is not whether multi weight is required, but rather would it be detrimental in any way.

Engine manufacturers knew best from amongst the available choices at the time. They had no crystal ball with which to gaze forward to the new oils and additives now available.

The question earlier about the engine's age is an important one. Oils have evolved quite a bit over the decades, and each new oil standard (API rating) is backwards compatible with previous standards. So in general, a modern 10W-30 oil is a suitable replacement for any straight weight oil from 10W to 30W. There are exceptions, but they are just that - exceptions.


And related to this, I have to wonder.... We get all worked up over what type of oil to use. Brand, weight, multi vs straight, etc. It's as bad as filter micron ratings and anchors. So I have to ask. Has anyone, at any time in their life, of the dozens and dozens of motors we have all owned over the years in various vehicles and machines, ever had one fail because they used incompatible oil?


Personally, I have never had a failure, or even heard of a failure that traces back to the wrong oil selection. And strictly my opinion - I think fretting over oil selection is one of the biggest non-issues in the world of engines. I think any reputable brand meeting an industry specification called for in your manual, or backwards compatible with your manual, is just fine. Then start the engine, and use it.

twistedtree said:

The question earlier about the engine's age is an important one. Oils have evolved quite a bit over the decades, and each new oil standard (API rating) is backwards compatible with previous standards. So in general, a modern 10W-30 oil is a suitable replacement for any straight weight oil from 10W to 30W. There are exceptions, but they are just that - exceptions.


And related to this, I have to wonder.... We get all worked up over what type of oil to use. Brand, weight, multi vs straight, etc. It's as bad as filter micron ratings and anchors. So I have to ask. Has anyone, at any time in their life, of the dozens and dozens of motors we have all owned over the years in various vehicles and machines, ever had one fail because they used incompatible oil?


Personally, I have never had a failure, or even heard of a failure that traces back to the wrong oil selection. And strictly my opinion - I think fretting over oil selection is one of the biggest non-issues in the world of engines. I think any reputable brand meeting an industry specification called for in your manual, or backwards compatible with your manual, is just fine. Then start the engine, and use it.

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The oil ratings as defined by the standards organizations are usually more about emissions requirements for on-road vehicles than about lubrication requirements for engines.

Some big truck diesels come with warranty coverage for one million miles. You know the oil is adequate for engine protection.

At 50mph would be twenty thousand hours.

It is fun that people get passionate about motor oil and anchors.

I would use 15W40 assuming you have a diesel engine. That is the grade that almost all the local fishermen use in their diesels. Texaco URSA, Chevron Delo 400 and Shell Rotella T are all good choices. 10W30 and 10W40 are generally gas grades and not really appropriate for a diesel.

what_barnacles said:

My Lehman manual recommends straight wt. oil, it has a pump and a filter.

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This oil pump is probably not prone to cavitation in the specified range for operating temperatures.

Detergent oil probably is specified.

Who knows? The specification may have been written so as to promote a certain company's brand of oil.

I'd send in an oil sample to see what the lab says. They can tell how the oil is performing and also give you an idea of your engine's condition. It's cheap and you get some peace of mind also.

My guess is that the oil you have been using is far more than adequate.

The only motors I know of with really specific oil requirements are the old Detroit Diesels that need a specific ash content as well as the correct grade. Delo 100 is good, but Delo 400 is not. Some Rotellas are good, some not depending upon date of mfg. Fleetguard is good, but only one specific part number.

I have 12V71TI’s and I just buy my oil in 5gal pails from DDA directly, ditto with coolant. It ends up costing a tiny bit more, but I know it’s the right stuff that way and the difference is really a small price to pay for peace of mind.

Just a little more info. My engine is 1981 or so, Yanmar 3HM. Designed as a raw water cooled engine though originally installed with keel cooling. It runs at 140-150 F. I hadn't thought about this before but at that temp the oil is also at that temp so the multi grade oil is not being used to its full range. Whatever that means.

TDunn said:

I would use 15W40 assuming you have a diesel engine. That is the grade that almost all the local fishermen use in their diesels. Texaco URSA, Chevron Delo 400 and Shell Rotella T are all good choices. 10W30 and 10W40 are generally gas grades and not really appropriate for a diesel.

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The difference between oil for a gas engine vs diesel is also in the rating, and is irrespective of weight. Sxxx oils are for gas engines, and Cxxx oils are for diesels. From there you pick whatever weight you want.

ak-guy said:

Just a little more info. My engine is 1981 or so, Yanmar 3HM. Designed as a raw water cooled engine though originally installed with keel cooling. It runs at 140-150 F. I hadn't thought about this before but at that temp the oil is also at that temp so the multi grade oil is not being used to its full range. Whatever that means.

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The problem is that during cold startup, the engine is not at those temperatures, the oil is thick and does not adequately flow so more wear occurs. Being in Alaska does not help.

Be sure what you buy is specified for compression ignition "C" ie diesels; rated CH-4 or higher. "S" type rated oils are for Spark ignition ie gasoline engines.
Read more here:


https://www.api.org/products-and-se...ations/oil-categories#tab_diesel-c-categories


https://www.api.org/products-and-se...ies-and-classifications/latest-oil-categories

From Blackstone Labs:

"If your oil is too light, the bearing metals can increase. If the oil is too heavy, the upper end metals can increase. The trick is to find the right viscosity for your particular engine, which is why we suggest following the manufacturer's recommendation."

Their position on the subject, of course, and limited in scope, but at least there's some explanation as to the potential harm (or lack thereof) from the wrong viscosity, from their oil analysis point of view.

https://www.blackstone-labs.com/oil-viscosity.php

With a sea water cooled engine , about 140F or below coolant keeps the salt from clogging the engine.

Single weight oil was probably specified as the oil will never get warm enough for the thicking agents to perform.

If you now have some sort of Fresh Water cooling switching to a 180F thermostat and using multi grade oil might be acceptable.

Many folks use single weight oil as there is more oil in the oil.

"Modern" oils are high detergent so the engine can eat its exhaust for the air police.
Some oils will contain up to 20% of their volume detergents , anti foam agents , rust inhibitors etc.

Old non EGR engines do not require these , so some folks prefer oil in the oil to a useless chemical pack.

I would check with Yanmar. They very well may have put out a service bulletin modifying their oil recommendations. Many engine manufacturers recommended single weight oil thru the late 80s early 90s before accepting the benefits of multi weight oil.

John

At times.... any oil is better then no oil.... that be said I drive diesels OTR big trucks from 15L motors to smaller chassis small 6.7L motors. Up until a few years ago the standard was 15w-40. Now I've read guys running 10w30 because of better mpg and no ill effects. The new 6.7l ford motor we use 10w30 syn and the Cummins and mercades still get 15w40 with 2 quarts of Lucas added. The benz has 340,000 miles on her and the Cummins is up to 200,000 road miles being driven local. Benz is changed at 10k miles the Cummins is when the computer says.

Imo change your oil in a good interval and it's how you run your motor. No need to be running it hard all day long and be gentle on the acceleration.

I would not be fearful to add a multigrade oil to your motor. See what would supersede a 20w oil and go from there. In my understanding the multi grades are for cold and hot oil viscosity ratings.

ak-guy said:

Just a little more info. My engine is 1981 or so, Yanmar 3HM. Designed as a raw water cooled engine though originally installed with keel cooling. It runs at 140-150 F. I hadn't thought about this before but at that temp the oil is also at that temp so the multi grade oil is not being used to its full range. Whatever that means.

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With these low temperatures the oil probably never gets hot enough to boil-off the condensation out of the oil. Without frequent changes your oil may be prone to sludge build-up.

johnrupp said:

Many engine manufacturers recommended single weight oil thru the late 80s early 90s before accepting the benefits of multi weight oil.

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It wasn't necessarily being slow to see the light. Engineers like to test and see what works before changing from a known safe regimen. It was often waiting until multigrade oils "did not suck," so to speak. Early on, in the 70s and into the 90s, they were often terrible. Very rudimentary stuff was used as VII's - viscosity index improvers - the particles that will expand when hot and thus modify the base oil's natural natural viscosity at that temperature into something thicker. Early on, chopped-up tennis shoes were even used. Yep.

Many of the early VIIs were just terrible and carboned up engines something horrible. Even now, as FF was describing above, you can have oil that is 20% "other stuff" that does no lubricate in order to achieve a wide viscosity spread - cheaper 5w-30s and also some synthetic 0w-XX oils are a whole lot of additive. These additive molecules are often enormous compared to base oil molecules and do not stand up to shear forces in the engine over time.

What FF said above is very relevant wrt the benefits of monograde oils in the right applications. If your climate conditions do not warrant 5w,0w winter ratings, you are doing your engine no favor by using them.

ak-guy said:

Just a little more info. My engine is 1981 or so, Yanmar 3HM. Designed as a raw water cooled engine though originally installed with keel cooling. It runs at 140-150 F. I hadn't thought about this before but at that temp the oil is also at that temp so the multi grade oil is not being used to its full range. Whatever that means.

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I have a 3HM35F, and the original manual. I agree that on page 13-4 it says use 30w from 68-95 degrees, but on the top of the next page in the first paragraph it says, "oil having a viscosity equal to that of SAE30, even at 98.9C is called SAE 10-30, or multigrade oil"


At the bottom of the page it says the "New" classification CB or CD grade should be used, introduced 1961 and 1955 respectively.



It summarizes the whole thing on page 13-6, by oil brand name, but it's useless because in 1981 they didn't know what would be available today.


1. You probaby can't find a CC or CD oil these days so you'll have to use a better, more moden oil.
2. Use 10-30 if you want to please the book, but really, if 30 is in the range of the viscosities go for it. Personally, I'd make sure there is a 10 in the multigrade spec given the low operating temperature.



BTW, on page it says the thermostat begins to open at 42C and is fully open at 52C, and the cooling water is maintained at that level. Have you checked the thermostat?

Have you tried the interweb???

https://shop.advanceautoparts.com/p...gclsrc=aw.ds&dclid=CPL_sJy9_NwCFcNgwQodussJTg

Oil

I have CAT 3116 diesels--vintage 1994. The manual specifies single viscosity 30wt or 40wt, and explains briefly that the multi-viscosity oils have undesireable additives for this motor.

twistedtree said:

(...)Has anyone, at any time in their life, of the dozens and dozens of motors we have all owned over the years in various vehicles and machines, ever had one fail because they used incompatible oil?(...)

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Yes I have, many times. In fact, I just finished rebuilding a Honda BF60 that seized the #1 crank bearing due to poor oil selection. That being said, you can pour pretty much *any* lipid into a Yanmar HM, and it'll keep on clacking and rattling and smoking like it used to.