Which Diesel Engine Oil To Use

[Comodave]

Yes, Rotella comes in 30 weight.

 

[High Wire]

Shell Rimula down under?

 

[NCheaven]

The manual suggestion

I went by the manual suggestion for viscosity, also deciding that Volvo recommending Volvo oil didn't make as much sense as going with top oil companies' published research. So, I read published info from Shell (Rotella) and Exxon - the pioneer in synthetic oils, Mobil 1. Reading as much as possible research from any source I could find - did you know that there is a study of lubricants called "Tribology"? I read that trade association's publications on line - anything I could find on lubricity, just for the fun of it. (Life of the party, don't you know.....)

The research I found covered so much about compensating for increasingly low sulfur fuels with excellent lubricity formulations and additives in the oil. But the bottom line is that synthetics hold up longer, have reduced risk of shearing, maintain viscosity longer, remove carbon build up more effectively, etc. There are even independent tests of diesel over the road fleet engine oil performance, where durability and fuel efficiency, reduced deposits, lower maintenance costs, longer engine life, etc., mean so much t o trucking companies' profitability. Believing that science does make a difference, and that the science is out there in spades builds confidence. So, I choose Exxon's Mobil 1 heavy duty diesel 15W40 or Shell's Rotella 15W40. Truthfully, in my April 15 to Thanksgiving boating year, a 20W-40 or even 20W-50 would be OK, and straight 30 with longer warm up periods would be OK here in paradise (North Carolina). But, the manual says 15W40, so I go with that in two highly reputable major oil companies top synthetic brands - Mobil 1 and Rotella 6, with the stats behind each to know I'm doing all that I can do in that department. I wish I could do so well in forecasting the weather.........

 

[catalinajack]

Oh boy, now just wait for a bunch of responses saying that synthetics are not necessary or worth the cost despite the science. The typical response - I've been using Dino oil for forty years with good results. Or - the manual says straight 30 weight. Yup, that's a good one, as if today's oils are the same as what was 40 years ago.

I went by the manual suggestion for viscosity, also deciding that Volvo recommending Volvo oil didn't make as much sense as going with top oil companies' published research. So, I read published info from Shell (Rotella) and Exxon - the pioneer in synthetic oils, Mobil 1. Reading as much as possible research from any source I could find - did you know that there is a study of lubricants called "Tribology"? I read that trade association's publications on line - anything I could find on lubricity, just for the fun of it. (Life of the party, don't you know.....)

The research I found covered so much about compensating for increasingly low sulfur fuels with excellent lubricity formulations and additives in the oil. But the bottom line is that synthetics hold up longer, have reduced risk of shearing, maintain viscosity longer, remove carbon build up more effectively, etc. There are even independent tests of diesel over the road fleet engine oil performance, where durability and fuel efficiency, reduced deposits, lower maintenance costs, longer engine life, etc., mean so much t o trucking companies' profitability. Believing that science does make a difference, and that the science is out there in spades builds confidence. So, I choose Exxon's Mobil 1 heavy duty diesel 15W40 or Shell's Rotella 15W40. Truthfully, in my April 15 to Thanksgiving boating year, a 20W-40 or even 20W-50 would be OK, and straight 30 with longer warm up periods would be OK here in paradise (North Carolina). But, the manual says 15W40, so I go with that in two highly reputable major oil companies top synthetic brands - Mobil 1 and Rotella 6, with the stats behind each to know I'm doing all that I can do in that department. I wish I could do so well in forecasting the weather.........

 

[NCheaven]

Thanks, Jack. The oils of the good old days didn't face the challenge of low sulfur fuel, higher compression ratios, and so many boats running at high speeds and high RPMs. Everybody gets to choose, but matching todays oils to todays low sulfur fuels and for some folks' higher speeds and RPM seems like a better idea, and science backs that up.

With Camano being a high displacement to LOA trawler, and my being a mostly hull speed operator aside from periodic 80% of WOT at the end of most days to clean out the exhaust, carbon build up is a particular concern for me, and the data on removing carbon is strongly in favor of synthetics.

Let's hope most boaters research and select oils and fuels/additives pertinent to their engines, manuals and usage.

 

[Nomad Willy]

NC heaven,
All of what you dug up is true and I’m aware of it.
But I stick w 30w dino as a function of need.

We don’t need the synthetic if we change oil often. Changing often is IMO more beneficial than extended change intervals because we get the contaminants out of the oil .. by removing the oil. Carbon, dirt, water, chemicals and other degradation elements like sheered oil molecules. Oil always turns black in time and I don’t think there’s any doubt it’s contaminated when that happens.

We run trawlers and our fluid temps stay very cool. No high temps. I run my boat at a 50% load and think that’s equal to or higher than most others here. That’s 50%load (not 50% rpm) and at those low loads we just don’t generate enough heat to need synthetic oil’s temperature stability. And that is synthetic oil’s main advantage. I think this is a true statement ... “syn oil is so temp stable it dos’nt need any viscosity stabilizers called viscosity improvers. Ever heard of a single weight synthetic oil? No ... because syn oil is a mv oil w/o any VI’s at all. At one time VI’s were rubber balls” .. don’t know what they are now.
VI are not a lubricant and do nothing to directly lubricate your engine. Lubricity is reduced by VI’s. Over the road trucks need multi-vis oil as they travel widely and encounter temps over a very wide range. Not so in our boats. No freezing temps at all.

Some say/think that mv is needed to help get the oil to the bearings during start-up. Not so at all IMO. An old wife’s tale so to speak. The lube oil is pumped by a gear to gear pump and since oil (in this context) is not compressible the oil volume pumped is constant as are the holes/galleries that the oil is pumped through. The thick oil gets to the bearings at the same rate/speed as thin oil.
Also the only lubrication the bearings have is the residual oil from when the engine was run last and if that was a higher viscosity oil better lubrication will be achieved at start-up.

So I change oil more often and use a single weight dino oil.

NChavan wrote;
“and the data on removing carbon is strongly in favor of synthetics.”
Haven’t heard that. Why wouldn’t changing oil more often be better in this regard?

 

[The MaryAnn]

15:40 was the correct oil for a Diesel engine, I wish you wouldn’t have responded if you didn’t know because you confused me and I ended up using 1040 in both engines (10 gallons) My mechanic said not to worry but all the same don’t interject opinions if you don’t know what your talking about. ��

 

[The MaryAnn]

I used SAE 1040 �� I hope I’m ok until my next oil change.

 

[The MaryAnn]

So is SAE 1040 ok? That’s what I used in both engines, I’m in southern California so it’s warm here so that’s why I didn’t use 1030��

 

[psneeld]

15:40 was the correct oil for a Diesel engine, I wish you wouldn’t have responded if you didn’t know because you confused me and I ended up using 1040 in both engines (10 gallons) My mechanic said not to worry but all the same don’t interject opinions if you don’t know what your talking about. ��

Someone here recommended 10W40?

 

[The MaryAnn]

It’s my fault for not knowing what bloody oil my boat uses, now I see someone said in the thread my motor doesn’t stomach 15:40 �� I used SAE 1040 so I hope I’m ok till the next oil change ��

 

[Scott Harris]

Hi Eric,

Just curious. How often do you change oil?

 

[psneeld]

This is what was said in post #8.....

"Its a rare diesel that doesn't stomach 15W40 Diesel rated oil...but there are a few.

If I can't find something else that is "required", it would do just fine."

Sorry if that confused you...even if it did, why listen to one post when so many others were different?

 

[Simi 60]

We do have Shell as a petroleum brand, their outlets sell oils.

But not Rotella

Here we have Rimula

 

[High Wire]

10w40 will be ok as long as the API cert begins with “C” for Compression and not “S” for spark. S types are for gas engines. Hope you saved one of the bottles.
If you are going to lose sleep over it, go to Walmart and buy Rotella T4 15w40.

 

[Nomad Willy]

Hi Eric,

Just curious. How often do you change oil?

Good question as I’m not a good record keeper. Sometimes I record it sometimes I don’t. There are changes I make that’s based on (if I can’t remember then it won’t hurt to change). Sometimes if I think it really has’nt been long I’ll just change the oil in the engine and not the filter.
I do that on my cars too especially if I’m about to make a trip. And it also has something to do how easy the filter is to get to.
My boat filter is easy to get to but it drools plenty of oil out.

Oil ages slowly and exact timing isn’t critical.

 

[Bacchus]

+1 to check BoatDiesel.com for a manual.
You can't go wrong following manufacturers recommendations.
You should be able to search to see what documents are available but will need to join to view / download them. Very worthwhile if you find info for your engine as you can then download and save them for future reference.

 

[Nomad Willy]

Rotell’s fine but it’s not a religion.

Brand makes little (when it does) difference in anything. At NAPA you can buy NAPA brand oil that is actually re-branded Valvoline oil. I consider Valvoline a high quality oil. Was going to switch to using it in my boat and cars in Alaska but found my usual oils (Castrol and RPM Delo) so let the Valvoline slide.

 

[O C Diver]

Oh boy, now just wait for a bunch of responses saying that synthetics are not necessary or worth the cost despite the science. The typical response - I've been using Dino oil for forty years with good results. Or - the manual says straight 30 weight. Yup, that's a good one, as if today's oils are the same as what was 40 years ago.

Nothing wrong with synthetic oils if the application requires them. Have over 10,000 hours on my Dodge pickup with the Cummins diesel. Everything is original except for alternator, water pump and power steering pump. It runs happily on non synthetic which is what the manufacturer specified.

The Deere in my boat is happy with non synthetic as the manufacturer specified.

Oil change on the Cummins is about $45 and maybe $50 on the Deere. If I was interested in extending oil change intervals, I'd probably buy a buy pass filter system.

Ted

 

[Bacchus]

I agree with Eric & Ted re both use of synthetics and single wt oils if you are not in colder temps.
Also - while all API ratings will state they are backward compatible it doesn't mean the latest API rating oil is the best for our application. These newer API ratings were designed & developed specifically for OTR applications with emission control systems - a very different animal than our use.
I'll attach a copy of the best oil article I've found for marina applications and one whose recommendations I try to follow.
It can also be found on my Bacchus website (link in signature) in the Links section - Cox Eng - Best Lubrication for Yacht Engines

 

[Nomad Willy]

Ted says re syn oils “if the application requires them”.
I don’t use any syn oil now but when flying ultralights early on I got on the syn bandwagon. The little 2-stroke engines ran often for a considerable time at WOT and the leanest mixture that wouldn’t seize the piston to the cylinder wall.
But our trawler engines run way cool. No need for syn oil.

And re your link Don it’s full of good stuff but I differ on the viscosity stuff.

 

[catalinajack]

Yup, just as I predicted.

NC heaven,
All of what you dug up is true and I’m aware of it.
But I stick w 30w dino as a function of need.

We don’t need the synthetic if we change oil often. Changing often is IMO more beneficial than extended change intervals because we get the contaminants out of the oil .. by removing the oil. Carbon, dirt, water, chemicals and other degradation elements like sheered oil molecules. Oil always turns black in time and I don’t think there’s any doubt it’s contaminated when that happens.

We run trawlers and our fluid temps stay very cool. No high temps. I run my boat at a 50% load and think that’s equal to or higher than most others here. That’s 50%load (not 50% rpm) and at those low loads we just don’t generate enough heat to need synthetic oil’s temperature stability. And that is synthetic oil’s main advantage. I think this is a true statement ... “syn oil is so temp stable it dos’nt need any viscosity stabilizers called viscosity improvers. Ever heard of a single weight synthetic oil? No ... because syn oil is a mv oil w/o any VI’s at all. At one time VI’s were rubber balls” .. don’t know what they are now.
VI are not a lubricant and do nothing to directly lubricate your engine. Lubricity is reduced by VI’s. Over the road trucks need multi-vis oil as they travel widely and encounter temps over a very wide range. Not so in our boats. No freezing temps at all.

Some say/think that mv is needed to help get the oil to the bearings during start-up. Not so at all IMO. An old wife’s tale so to speak. The lube oil is pumped by a gear to gear pump and since oil (in this context) is not compressible the oil volume pumped is constant as are the holes/galleries that the oil is pumped through. The thick oil gets to the bearings at the same rate/speed as thin oil.
Also the only lubrication the bearings have is the residual oil from when the engine was run last and if that was a higher viscosity oil better lubrication will be achieved at start-up.

So I change oil more often and use a single weight dino oil.

NChavan wrote;
“and the data on removing carbon is strongly in favor of synthetics.”
Haven’t heard that. Why wouldn’t changing oil more often be better in this regard?

 

[catalinajack]

Your concern with viscosity improvers is a big "so what". But, for those who are still concerned with this misplaced concern and who want the benefits of a synthetic in a straight grade, AMSOIL makes a straight 30 with no viscosity improves. Frequent oil changes are a collosal waste not to mention it's a big pain in the ass.

NC heaven,
All of what you dug up is true and I’m aware of it.
But I stick w 30w dino as a function of need.

We don’t need the synthetic if we change oil often. Changing often is IMO more beneficial than extended change intervals because we get the contaminants out of the oil .. by removing the oil. Carbon, dirt, water, chemicals and other degradation elements like sheered oil molecules. Oil always turns black in time and I don’t think there’s any doubt it’s contaminated when that happens.

We run trawlers and our fluid temps stay very cool. No high temps. I run my boat at a 50% load and think that’s equal to or higher than most others here. That’s 50%load (not 50% rpm) and at those low loads we just don’t generate enough heat to need synthetic oil’s temperature stability. And that is synthetic oil’s main advantage. I think this is a true statement ... “syn oil is so temp stable it dos’nt need any viscosity stabilizers called viscosity improvers. Ever heard of a single weight synthetic oil? No ... because syn oil is a mv oil w/o any VI’s at all. At one time VI’s were rubber balls” .. don’t know what they are now.
VI are not a lubricant and do nothing to directly lubricate your engine. Lubricity is reduced by VI’s. Over the road trucks need multi-vis oil as they travel widely and encounter temps over a very wide range. Not so in our boats. No freezing temps at all.

Some say/think that mv is needed to help get the oil to the bearings during start-up. Not so at all IMO. An old wife’s tale so to speak. The lube oil is pumped by a gear to gear pump and since oil (in this context) is not compressible the oil volume pumped is constant as are the holes/galleries that the oil is pumped through. The thick oil gets to the bearings at the same rate/speed as thin oil.
Also the only lubrication the bearings have is the residual oil from when the engine was run last and if that was a higher viscosity oil better lubrication will be achieved at start-up.

So I change oil more often and use a single weight dino oil.

NChavan wrote;
“and the data on removing carbon is strongly in favor of synthetics.”
Haven’t heard that. Why wouldn’t changing oil more often be better in this regard?

 

[Bacchus]

Ted says re syn oils “if the application requires them”.
I don’t use any syn oil now but when flying ultralights early on I got on the syn bandwagon. The little 2-stroke engines ran often for a considerable time at WOT and the leanest mixture that wouldn’t seize the piston to the cylinder wall.
But our trawler engines run way cool. No need for syn oil.

And re your link Don it’s full of good stuff but I differ on the viscosity stuff.

I'm with you and Ted - Syn if required / specified - That's what I run in my car as its speced and sees a wider use temp range.

I'm not sure if / where we differ on Viscosity?
The article explains Vis but says little re recommending vis other than follow mfg recommendation and it certainly depends on environment.
My personal preference for boat diesel is single Vis as temps are pretty constant and don't need multi vis - I thought that was your position as well?
I don't see any advantage to multi vis where modifiers are used but not req'd as they just replace base oil that provides the lube.

 

[NCheaven]

Always a lively discussion topic! Fun!

The data on capturing carbon came from an Exxon research study. Their website research on diesel engine oil is pretty interesting.

Temps on Boatwright are pretty constant, except the very rare times I go above 3200 rpm. The temp range in the engine manual is something like 171-194, and mine stays very close to the lower number below 3200 rpm, but goes closer to 194 as I pass through 3400 up to WOT of 3750 (last season, 2 year old bottom paint but cleaned, full load). My car and truck temp stays very flat except the 4cyl. hybrid Buick might run higher on a long steep hill. I change oil at 5,000 to 7,000 on car and truck, and once a season on the boat. 4 cyl has 126,000 miles, 2000 model Chevy HD 4x4 truck has 256,000 miles, some hauling horse trailer, no engine issues on either, both vehicles still on original spark plugs, both exclusive Mobil 1 5W30. The once a season change for the boat is in the late fall to clean out any acid that might have formed during "the season", although that might be an old wives tale about acid build up left in dormant oil coming out of solution to damage an engine.

Good contributions from everyone, seems like most of us are comfortable, "right or wrong, but never in doubt!" Main thing is that our contributors have thought through the options, and have a reason for their choices - that's good thing.

For "enthusiasts" on this subject, visit STLE - the Society of Tribologists and Lubrication Engineers. Their web site has "white papers" on many subjects, including marine diesel engines, although most of that relates to commercial marine engines. Some of my opinions come from dark and stormy off-season nights spent reading up on diesel lubrication there and elsewhere. Fix a pot of black coffee and have fun!

Is it spring yet?

 

[NCheaven]

By the way, Rotella's product comparison between T6 full synthetic and T5 synthetic blend notes T6's improved Cleanliness/Deposits, Wear Protection, and Better Oxidation Protection. Their T5 synthetic blend is noted for a 55% reduction in deposits below the CK-4 API standard. So, assuming their marketing department talks to their Tribology Engineers and Product Liability lawyers, at least Shell Rotella folks believe there is a difference between mineral oil, blends and full synthetic, beyond high temperature sheer reduction.

Mobil Delvac full synthetic is claimed to have 40%+ more anti wear and and anti oxidation additives than their Delvac 1300 blend, and the 1300 blend is claimed to have numerous performance advantages over Mobil's mineral oil. So, again, an oil giant believes that their full synthetic has performance advantages.

How much of this is relevant to our mostly moderate load engines is a topic for endless discussion. After all, I don't see a lot of posts about engine failure relating to lubricants, although soot accumulation in exhaust systems is a noted common problem. But, I'll stick with Exxon/Mobil or Shell Rotella full synthetic 15W40 (engine manual recommended viscosity).

 

[Nomad Willy]

Glad you guys are still reading my posts.

Thought I was using syn on my 06 Avalon. It’s so cheap I go to the dealer. It’s Mobil 1. Didn’t know Mobil even made dino but eventually I found out. At first I was disappointed. But then I thought about what I say on TF and realized the duty cycle for my car was the same as my boat. Live in a moderate climate, drive at very moderate engine loads and don’t experience hot weather. But the Mobil 1 dino they put in my Avalon is 5-w30. So I decided I had no need for syn oil for my Avalon. My other cars (95 Camry and 87 Nissan Stanza) both use 10-30w high milage dino oil.

NCheaven,
Your coolant temp isn’t your engine temp. The coolant is kept much hotter than it normally would be by the thermostat. If you had a gauge for your oil temp .. that would be very close to the real engine temp. And the lube oil system is also a cooling system. But w/o a thermostat. The temp of the pistons and valves would be engine temp but we have no indicators for them.

Don,
Viscosity of lube oils for marine engines almost always recommend 30w oil. They recommend 15-40w also and other viscosities as well. They realize most people will use MV but 30w is recommended just like 15-40w. Since most people think more modern oils are better .. just because they ..usually are. And most people think modern things are universally better. But as I try to point out “better” .. at what? MV oils are needed in certain or most applications like a truck or most cars. But it’s not needed and actually a bit better to just use straight weight oil in our boats.

Cat Jack,
I’m surprised there is a straight weight syn oil. I wonder if it is. Since syn oil has MV properties w/o any viscosity improvers it seems to me that syn oil w/o VI would test as a MV and therefore need to be classified as a MV oil. How can a syn oil test like straight wight oil?
A straight syn oil w/o VI if it had the properties of 30w dino oil at the high temps specified would test at something other than 30w at the lower temp range of testing.

But it even gets more complicated than that. Syn oil is made from various base stocks that (I’m sure) have various viscosity properties.
So I don’t understand syn straight weight oil.

 

[catalinajack]

Nomad Willy, this is the product description.


AMSOIL Synthetic 10W-30/SAE 30 Diesel Oil (ACD) is formulated with premium synthetic base oils that exceed both 10W-30 multi-grade and SAE 30 straight-grade viscosity requirements for outstanding performance in modern and older diesel engines. Unlike conventional SAE 30 motor oils, AMSOIL ACD has a naturally high viscosity index and
does not contain paraffin (wax). It has a -36°F pour point and qualifies for SAE 10W, making it an “all season” multi-grade lubricant with a wide operating temperature range. AMSOIL ACD is formulated without viscosity index improvers (VI). This shear stable formulation stops viscosity loss and associated bearing and cylinder bore wear. AMSOIL ACD contains premium additives with a high 12 TBN to neutralize acids from blow-by, exhaust gas recirculation (EGR) and high sulfur diesel fuels. It protects against damaging piston deposits, ring sticking and sludge.

Glad you guys are still reading my posts.

Thought I was using syn on my 06 Avalon. It’s so cheap I go to the dealer. It’s Mobil 1. Didn’t know Mobil even made dino but eventually I found out. At first I was disappointed. But then I thought about what I say on TF and realized the duty cycle for my car was the same as my boat. Live in a moderate climate, drive at very moderate engine loads and don’t experience hot weather. But the Mobil 1 dino they put in my Avalon is 5-w30. So I decided I had no need for syn oil for my Avalon. My other cars (95 Camry and 87 Nissan Stanza) both use 10-30w high milage dino oil.

NCheaven,
Your coolant temp isn’t your engine temp. The coolant is kept much hotter than it normally would be by the thermostat. If you had a gauge for your oil temp .. that would be very close to the real engine temp. And the lube oil system is also a cooling system. But w/o a thermostat. The temp of the pistons and valves would be engine temp but we have no indicators for them.

Don,
Viscosity of lube oils for marine engines almost always recommend 30w oil. They recommend 15-40w also and other viscosities as well. They realize most people will use MV but 30w is recommended just like 15-40w. Since most people think more modern oils are better .. just because they ..usually are. And most people think modern things are universally better. But as I try to point out “better” .. at what? MV oils are needed in certain or most applications like a truck or most cars. But it’s not needed and actually a bit better to just use straight weight oil in our boats.

Cat Jack,
I’m surprised there is a straight weight syn oil. I wonder if it is. Since syn oil has MV properties w/o any viscosity improvers it seems to me that syn oil w/o VI would test as a MV and therefore need to be classified as a MV oil. How can a syn oil test like straight wight oil?
A straight syn oil w/o VI if it had the properties of 30w dino oil at the high temps specified would test at something other than 30w at the lower temp range of testing.

But it even gets more complicated than that. Syn oil is made from various base stocks that (I’m sure) have various viscosity properties.
So I don’t understand syn straight weight oil.

 

[NCheaven]

I think we all know that the temp gauge is just an indication, not anywhere near internal temp - just a good directional indicator. Some boats have sensor for exhaust temp, but not mine. But we know that combustion temps are multiples higher than coolant temp. Far higher internal temps support the concept of having a heat shear resistant oil - especially for turbos, etc. The time needed to shear some oils is not very long, and the time differs among various grades and API ratings.

Per the website, Mobil 1 is full synthetic. There are other Mobil oils that are not.
Mobil Delvac grades marketed toward diesel and some other applications range from full synthetic to mineral oil.

 

[Woodland Hills]

Just a reminder: if your motor is a two-stroke Detroit Diesel disregard everything in this thread. You need a low ash single weight oil made for two-stroke diesels, but you already knew that, didn’t you?