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mainekneeboarder

Oil viscosity?

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mainekneeboarder

With all the oil talk lately going on, it got me to thinking about why Indmar says to use such a high viscosity oil? There seems to be some very intelligent people on this forum, (and some that just like to debate a topic) and I would love to here your thoughts on the subject. I am a thin oil person myself and always have been, I run very low viscosity in everything I own because I believe in lower viscosity oils, and because of our temps being a bit lower then most in the country. I'm not here to argue about it, but rather maybe learn something. I have been using low viscosity oils for years and have had no trouble, being a younger guy I have even had alot of old school guys badger me about it (friendly ribbing of course) at the race track, but have seen a few of them convert from the norm of 20-50 to something lighter lately. It seems even most of the new manufactures are recommending 5-30 or 5-20 now and have been for a while. So why does Indmar recommend 15-40 or more still?

Just for fun, what does everyone use?

Boat= 10-30 synthetic

Truck= 5-30 summer, 0-20 winter synthetic.

ATV= 10-30 summer, 5-20 winter. synthetic blend

Please keep the debating (arguing) to a minimum, I love to read informative reasoning, but loose interest when it turns in a different direction.

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Deephaven

Ever thought of what happens to low viscosity oils when they heat up beyond the range they are meant to be run? How about in particular in a device that was designed with clearances for a certain viscosity?

Indmar specifies a viscosity based on normal conditions which in general are pretty common among regions as what temperatures don't fluctuate all that much.

What I'd like to know is why you believe in lower viscosity and what science you are using to back that up. If its because thinner is better you should rethink your choices.

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85 Barefoot

Ever thought of what happens to low viscosity oils when they heat up beyond the range they are meant to be run? How about in particular in a device that was designed with clearances for a certain viscosity?Indmar specifies a viscosity based on normal conditions which in general are pretty common among regions as what temperatures don't fluctuate all that much.

What I'd like to know is why you believe in lower viscosity and what science you are using to back that up. If its because thinner is better you should rethink your choices.

While that can hold some water for discussion, it doesn't when considering that cars, which run at a far higher operating temperature are recommended for thinner oil than our boats. In other words, temperature range is not the issue.

My guess is that because the duty cycle of our engines is often high load, high rpms for long duration, a thicker oil is the only way to provide adequate protection for sufficient duration.

I run 5w-20 in the truck (5.7 gasser)

straight 40 weight in the 8.1, and 15w-40 in the monsoon.

As for low viscosity superiority, if climate demands it, thinner is absolutely better.

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ColinP

I have a Merc 350 and I ran a crankcase full of 5w20 because I had cases of it sitting around. After a long hot weekend (burned about 60 gallons of gas) with ballast in the boat, I was down almost a quart and had a mess of oil film all over the spark arrestor and carb. Usually I can go an entire season without topping off the oil.

Edited by ColinP

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Malibudude

I run 15w-40 DELO in the boat and 5w-30 Napa Synthetic in the truck/car. No need to change viscosity in a mild climate in norcal.

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mainekneeboarder

Ever thought of what happens to low viscosity oils when they heat up beyond the range they are meant to be run? How about in particular in a device that was designed with clearances for a certain viscosity?

Indmar specifies a viscosity based on normal conditions which in general are pretty common among regions as what temperatures don't fluctuate all that much.

What I'd like to know is why you believe in lower viscosity and what science you are using to back that up. If its because thinner is better you should rethink your choices.

No science, just that I believe most engine bearing damage ocures during start-up, motors I have seen come apart using lower viscosity oils have normally been in good condition, with no sledging issues or oil burning on issues, and it seems you never hear of a bearing knock issue now like we used to, along with the fact that I use my trucks as TRUCKS and over 196,000 miles on the last one and 208,000 on the current one, using low viscosity oils, I have still not had an engine issue. I don't believe thinner is better, I believe in my case, in our environment, it works better for me. I am an open minded person and truly believe oils have gotten better over the years and think some people are still stuck in the old school ways of thicker is better. I am in no way indicating that Indmar is in this line of thinking, but am just wondering why they are still calling for thicker oil. As I said most car manufactures have gone to 5-30 long ago with some at 5-20 now?

you should rethink your choices.

I'm not hear to argue about it, I have had very little engine issues with thinner oils, and most likely will not "rethink" my oil preference because of comments like this! I will how ever stay open minded and take in all others intelligent thoughts on the subject, which is why I started the topic in the first place.

My guess is that because the duty cycle of our engines is often high load, high rpms for long duration, a thicker oil is the only way to provide adequate protection for sufficient duration.

This was more along the lines of what I was thinking also.

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Woodski

I use a 5W-30 synthetic, no oil consumption for the season (75 hours+/-) and over 800 total hours on the engine. GM small blocks are validated for the 5W-30 oil viscosity, since cold weather is not a big issue I could run a higher leading number. Main usage is slalom and barefoot so run at higher engine speed but not a high load. Oil temp is related to engine rpm so barefooting would create my highest oil temps although the duration is shorter than a long slalom run. I have checked the pan temp when finished and the water temp is around 160 degrees F, the pan surface temp is never over 200 deg. F. I do carefully warm up the engine prior to a slalom or footing run. As important would be a good oil filter, the Napa Gold / Wix filters are excellent, and I use the one for the pickup truck (largest size).

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jkendallmsce

While that can hold some water for discussion, it doesn't when considering that cars, which run at a far higher operating temperature are recommended for thinner oil than our boats. In other words, temperature range is not the issue.

My guess is that because the duty cycle of our engines is often high load, high rpms for long duration, a thicker oil is the only way to provide adequate protection for sufficient duration.

I run 5w-20 in the truck (5.7 gasser)

straight 40 weight in the 8.1, and 15w-40 in the monsoon.

As for low viscosity superiority, if climate demands it, thinner is absolutely better.

I agree...but wonder why Indmar suggests to put 50W in the hammerhead..if you were having oil pressure issues?? Is the HH just that much of a looser engine?

And not trying to take away from this discussion, but is synthetic really that much better that conventional?? I have had rigs with over 200k miles using convenctional oils.

Edited by jkendallmsce

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ColinP

While not scientific at all, I know synthetic is a b**** to clean up off of asphalt when compared to conventional oil.

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khelfrich

inside a motor the bearings used are journal bearings all your mains and rods there are benefits of both thin and thick oils, journal bearings work off an oil film thickness and the crank is actually riding on a film over the Babbitt in straight protection the thicker the oil the better bearings with thicker oils can take higher loads, the draw back of the thick oil is that there is more resistance or drag in the motor, high rpm is not necessarily higher load and with cars now a days revving higher and having lower torque that loads on the bearings are less, another reason car engines are going to lower weight oils is to make them more efficient to meet EPA requirements for emissions and fuel economy requirements. boats don't have to meet these i mean there boats and they drink fuel, also boat motors are always working to move a boat there is no coasting like in a car so they are always under very high loads and lots or torque being used creating lots of bearing load.

if you look at diesel engines they run very low rpm and high weight oil and create a ton of torque the longer the stroke of the motor the slower it spins due to the mas piston speed limitations that are the same on all motors. at low rpm the power being generated in putting high loads on the bearings demanding thick oil. also look at all big truck engines or any high torque engine they are mostly all inline motors which give more bearings supporting the crank think about a V8 vs and inline 6 the v8 has 5 mains and the I6 has 7 more bearings on the crank means less load on the individual bearings.

and back to the same engine in a car having a lower weight oil than in a boat. again a trade off to meet the requirements on the EPA and still last a good bit of time they lower the oil weight its a compromise in the car/ truck they don't see the constant load in a boat it is all constant load.

hope that helps clear some stuff up

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CumminsBu

inside a motor the bearings used are journal bearings all your mains and rods there are benefits of both thin and thick oils, journal bearings work off an oil film thickness and the crank is actually riding on a film over the Babbitt in straight protection the thicker the oil the better bearings with thicker oils can take higher loads, the draw back of the thick oil is that there is more resistance or drag in the motor, high rpm is not necessarily higher load and with cars now a days revving higher and having lower torque that loads on the bearings are less, another reason car engines are going to lower weight oils is to make them more efficient to meet EPA requirements for emissions and fuel economy requirements. boats don't have to meet these i mean there boats and they drink fuel, also boat motors are always working to move a boat there is no coasting like in a car so they are always under very high loads and lots or torque being used creating lots of bearing load.

if you look at diesel engines they run very low rpm and high weight oil and create a ton of torque the longer the stroke of the motor the slower it spins due to the mas piston speed limitations that are the same on all motors. at low rpm the power being generated in putting high loads on the bearings demanding thick oil. also look at all big truck engines or any high torque engine they are mostly all inline motors which give more bearings supporting the crank think about a V8 vs and inline 6 the v8 has 5 mains and the I6 has 7 more bearings on the crank means less load on the individual bearings.

and back to the same engine in a car having a lower weight oil than in a boat. again a trade off to meet the requirements on the EPA and still last a good bit of time they lower the oil weight its a compromise in the car/ truck they don't see the constant load in a boat it is all constant load.

hope that helps clear some stuff up

This guy^^^ thinks like me and I couldn't have said it better.

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Soon2BV

"At cold temperatures, the polymers are coiled up and allow the oil to flow as their low numbers indicate. As the oil warms up, the polymers begin to unwind into long chains that prevent the oil from thinning as much as it normally would. The result is that at 100 degrees C, the oil has thinned only as much as the higher viscosity number indicates. Another way of looking at multi-vis oils is to think of a 20W-50 as a 20 weight oil that will not thin more than a 50 weight would when hot."

The multiweight oil lets the oil quickly start to flow and lubricate the engine as soon as it is started. As the engine and oil warms up, the oil provides the protection the engine needs for the speeds, clearances, and power the engine is producing.

As an engineer, I am confident that the team at Indmar designed and tested the product for the intended use. Indmar designed these engines to be used in boats, not cars. They know how the engines are used, they know the clearances hot and cold on all the moving parts. I am sure they tested their designs and then recommend specific oils and fuels to get the best performance from the engine.

I always find it interesting when users question / ignore the advice from the people who know the most about the product ....

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mainekneeboarder

inside a motor the bearings used are journal bearings all your mains and rods there are benefits of both thin and thick oils, journal bearings work off an oil film thickness and the crank is actually riding on a film over the Babbitt in straight protection the thicker the oil the better bearings with thicker oils can take higher loads, the draw back of the thick oil is that there is more resistance or drag in the motor, high rpm is not necessarily higher load and with cars now a days revving higher and having lower torque that loads on the bearings are less, another reason car engines are going to lower weight oils is to make them more efficient to meet EPA requirements for emissions and fuel economy requirements. boats don't have to meet these i mean there boats and they drink fuel, also boat motors are always working to move a boat there is no coasting like in a car so they are always under very high loads and lots or torque being used creating lots of bearing load.

if you look at diesel engines they run very low rpm and high weight oil and create a ton of torque the longer the stroke of the motor the slower it spins due to the mas piston speed limitations that are the same on all motors. at low rpm the power being generated in putting high loads on the bearings demanding thick oil. also look at all big truck engines or any high torque engine they are mostly all inline motors which give more bearings supporting the crank think about a V8 vs and inline 6 the v8 has 5 mains and the I6 has 7 more bearings on the crank means less load on the individual bearings.

and back to the same engine in a car having a lower weight oil than in a boat. again a trade off to meet the requirements on the EPA and still last a good bit of time they lower the oil weight its a compromise in the car/ truck they don't see the constant load in a boat it is all constant load.

hope that helps clear some stuff up

Very well put, and this is why I assumed Indmar was calling for higher viscosity oils then most do. But, Even Ford has recommended 10-30 in there diesels in cold areas for a while now, and Chevy even states " DO NOT use other viscosity oils such as SAE 10-40 SAE 20-50." high lighting "do not". They call for 10-30 above 0 DEG. and 5-30 below in there duramax diesel.

"At cold temperatures, the polymers are coiled up and allow the oil to flow as their low numbers indicate. As the oil warms up, the polymers begin to unwind into long chains that prevent the oil from thinning as much as it normally would. The result is that at 100 degrees C, the oil has thinned only as much as the higher viscosity number indicates. Another way of looking at multi-vis oils is to think of a 20W-50 as a 20 weight oil that will not thin more than a 50 weight would when hot."

I thought the higher viscosity oils had more (I forget all the actual names, VI? Viscosity Improvers) additives in them that break down quicker under high load/shear/heat conditions? Leaving you with a very poor oil that doesn't resist thinning with temp? From what I understand straight SAE oils have no additives, along with group 4 Synthetics, and have the best resistance to breaking down, but obviously not the range of multi viscosity oil. And that lower Viscosity oils have less additives, allowing them to hold there values longer? I understand the first viscosity is the cold weather number for start up, and the second number is the viscosity at 210 degrees, but I thought as both numbers went up (15-40) and the more they separated (20-50) is when you had an oil with more (VI?) additives and it was more prone to breaking down easier in high load applications (like our boat engines are used?) This I thought is the reason most manufactures have gone to thinner oils with less additives.

I always find it interesting when users question / ignore the advice from the people who know the most about the product ....

I'm not ignoring Indmar, but more taking an assumption that their recommendations are based on a climate 20-30 degs. warmer then ours usually is? We used the boat Sunday, and when we started it the air temp was 56 and water temp of 61. I still beleave, in our climate more engine damage occurs at start-up with thicker oils? Even at operating temps I would think our engine oil temp would be 20-30 deg cooler then most areas?

We have allot of old time fishermen getting up in the winter at 4:30-5:00 when the temps are often below 0deg and starting there diesel trucks, alot of them would tell you are crazy if you told them GM recommended 5-30 in their diesel engine for motor oil! It seems like an "old school way of thinking" that running thinker oil is just better? It just seems that as we learn more about oils and improve engines, most manufactures are recommending lower viscosity oils, and was just wondering why Indmar was staying with 15-40 which seems very high compared to most? I'm sure that they assume a boat is used mainly in the warm weather has something to do with it?

There is some very good reading so far in this topic, and some good explanations so far to help understand it better. I never could have put what i did know into words like you guys have, thanks.

Edited by mainekneeboarder

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shawndoggy

Just as an FYI, PCM does recommend 5w30 where the ambient operating temp is below 50* F. AFAIK, the internals on the PCM 5.7 and Indmar's 5.7 are identical, no? It's just what's hung on the motor for marinization and the ecm tune which vary?

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Soon2BV

"The most common diesel use oil is 15W/40. It is an SAE 15W oil with a VI additive that leaves it the thickness of an SAE 40 weight at operating temperature. What makes an

oil a diesel-use oil (rather than automotive-use) is the level of additives used. Diesels require heavier levels of dispersant and anti-wear additives. These heavier additive

levels are objectionable for automotive engines since they may interfere with the emission controls mandated by the EPA."

OK, so I did some more reading. The note above is a copy from another website and explains why the diesel grade fuel can be used in these engines.

Another good point is that the "15W" does not mean the oil is "15" weight oil when cold. The 15W number is a rating of the oils ability to flow and provide lubrication when cold. A 5W flows easier than a 10W, and a 10W easier than a 15W. There is a group of specialized tests that are done to determine this rating (it is not just a viscosity test. Since true viscosity tests are done at 100C, it wouldn't make sense.)

The 40 weight oil is the viscosity at 100C (212F). So, it could be the reason that the 40 weight oil is recommended is that the engine is operating a little cooler (210F vs 160F) than a typical automotive engine, so at our operating temperature the 40 is probably something in the 30's range.

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mainekneeboarder

"The most common diesel use oil is 15W/40. It is an SAE 15W oil with a VI additive that leaves it the thickness of an SAE 40 weight at operating temperature. What makes an

oil a diesel-use oil (rather than automotive-use) is the level of additives used. Diesels require heavier levels of dispersant and anti-wear additives. These heavier additive

levels are objectionable for automotive engines since they may interfere with the emission controls mandated by the EPA."

OK, so I did some more reading. The note above is a copy from another website and explains why the diesel grade fuel can be used in these engines.

Another good point is that the "15W" does not mean the oil is "15" weight oil when cold. The 15W number is a rating of the oils ability to flow and provide lubrication when cold. A 5W flows easier than a 10W, and a 10W easier than a 15W. There is a group of specialized tests that are done to determine this rating (it is not just a viscosity test. Since true viscosity tests are done at 100C, it wouldn't make sense.)

The 40 weight oil is the viscosity at 100C (212F). So, it could be the reason that the 40 weight oil is recommended is that the engine is operating a little cooler (210F vs 160F) than a typical automotive engine, so at our operating temperature the 40 is probably something in the 30's range[/b].

Ahh, very good point and one I hadn't thought of. This is exactly why I like to hear others opinion on stuff.

I have read before that the higher viscosity oils have more additives to them which cause them to break down faster, but have never heard any time frames, or how much faster at a certain temp, or if it breaks down faster because of not warming up enough, or starting in colder weather?

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mainekneeboarder
Another good point is that the "15W" does not mean the oil is "15" weight oil when cold. The 15W number is a rating of the oils ability to flow and provide lubrication when cold. A 5W flows easier than a 10W, and a 10W easier than a 15W. There is a group of specialized tests that are done to determine this rating (it is not just a viscosity test. Since true viscosity tests are done at 100C, it wouldn't make sense.)

This is the part about Indmars recommendations of 15-40 that I find the most odd for our climate, what temp is it tested at to figure it performs as that viscosity? Is it 50deg.? Thats fairly cold in alot of states, or is it 0deg? All I have ever read is "oils with W are tested at a colder temperature" I have never seen an actual deg#.

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mainekneeboarder
Viscosity index indicates how much of a lubricant's viscosity will change according to changes in temperature between 40 deg. C (104 deg. F) and 100 deg. C (212 deg. F), which roughly define the normal temperature range of most operations.

for example, a 5W-30. "W" means winter. In winter weather the 0W oil will flow like a 0W oil, and the 5W will flow like a 5W oil and a 10W will flow like a 10W oil just until the engine warms up. In order to understand the differences you must first understand that the numerical values given to these various weight oils are strictly empirical numbers.

This leads to the next topic: many people also ask us if the 0W-30 is too thin a viscosity oil for high ambient temperature operation. The answer is absolutely not! Thicker viscosity oils are not always necessarily better since in addition to its' various engine lubrication functions, an oil must also effectively transfer heat. Only about 60% of an engines cooling is performed by the engine coolant, and only on the upper half of the engine. The remaining 40% of an engines cooling is performed mainly by the engine oil.

Multi-grade motor oils perform a great service not being too thick at cold startup to prevent engine wear by providing more instantaneous oil flow to critical engine parts. However, there is a draw back. These additives shear back in high heat or during high shear force operation and break down causing some sludging.The more VI additives the worse the problem which is why auto manufacturers decided to steer car owners away from motor oils loaded with VI additives like the 10W-40 and 20W-50 viscosities.

The less change a motor oil has from high to low temperatures gives it a high Viscosity Index. Synthetic motor oils that are made from Group IV (4) PAO base stocks have Viscosity Indexes of more than 150 because they are manufactured to be a lubricant and don't have the paraffin that causes the thickening as they cool. But petroleum based motor oils (Group I (1) & II (2)) usually have Viscosity Indexes of less than 140 because they tend to thicken more at the colder temperature due to the paraffin despite the addition of Viscosity Improving additives. The higher the Viscosity Index number the less thinning and thickening the motor oil has. In other words, high number good, low number bad. Low numbers thicken more as they cool and thin more hot. You see these Viscosity Index ratings posted on data sheets of motor oils provided by the manufacturer.

As already mentioned, VI improving additives can shear back under pressure and high heat conditions leaving the motor oil unable to protect the engine properly under high heat conditions and cause sludging. Also there is a limit to how much viscosity improving additives can be added without affecting the rest of the motor oil's chemistry. Auto manufacturers have moved away from some motor oils that require a lot of viscosity improving additives, like the 10W-40 and 20W-50 motor oils, to blends that require less viscosity additives like the 5W-20, 5W-30 and 10W-30 motor oils. Because stress loads on multi viscosity motor oils can also cause thinning

I did some research last nite to refresh my memory of stuff I had read and to try and find out what the low temp test was done at. It says its done at 104deg., I'm not sure if the oil gets thinner still at lower temps or not? These are all copy and past of some of the stuff I read. Alot of this stuff was rite on Amsoil's site, there is some very good info here. Some of what I posted touches on why synthetics are considered better, (someone asked about that).

Going off Soon2BV's suggestion that the oil in our boat may be thinner because of the lower temps they run at does seem acceptable, considering the low number test is done so high of a temp., (I assumed it would have been lower)?

Sorry for the long post.

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85 Barefoot

I did some research last nite to refresh my memory of stuff I had read and to try and find out what the low temp test was done at. It says its done at 104deg., I'm not sure if the oil gets thinner still at lower temps or not? These are all copy and past of some of the stuff I read. Alot of this stuff was rite on Amsoil's site, there is some very good info here. Some of what I posted touches on why synthetics are considered better, (someone asked about that).

Going off Soon2BV's suggestion that the oil in our boat may be thinner because of the lower temps they run at does seem acceptable, considering the low number test is done so high of a temp., (I assumed it would have been lower)?

Sorry for the long post.

it gets thicker, why is why the balance of something thick enough tp provide protection yet thin enough to flow at low temps is the challenge.

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mainekneeboarder

it gets thicker, why is why the balance of something thick enough tp provide protection yet thin enough to flow at low temps is the challenge.

Bad wording on my part. I know the oil thickens as it gets colder, reason why I run 0W in the winter, (try pouring some into a plow truck that leaks a little, after the oil has been sitting in 10deg weather, its like waiting for molasses, this is why I don't completely understand the multi viscosity changing thing), I was wondering if the chemicals/additives react below the specified 104deg to still flow less then tested at 104deg? If a, 5w-30 is 30 viscosity at 210deg, and performs/flows like 5W at 104deg, does it change all the way down to 0deg?

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