Oil Viscosity and Boat engines

This should be fun

Benefits of Lower Viscosity oils:

1. faster oil flow on startup.
2. faster oil flow in colder weather.
3. More efficient flow in tighter tolerances (Lifter bores, tighter bearing clearances, etc)
4. Less viscous drag.. More HP

And as for Higher visc oils:

1. Thicker oil wedge for bigger clearances (Boats).
2. Higher oil pressure.
3. Better protection than lower Visc oils.

What about viscosity and oil filters, bypass valves, Coolers, and of course Oil temperature? :yikes

What do you run in your Boat, and what engine does it have?

Tcw3... Key is to change it with every fuel up

Kendall straight 40W in the blower motors in my Formula and Brad Penn multi vis in the motor Larry Peto built for my Southwind.

Lunatic Fringe said:

Kendall straight 40W in the blower motors in my Formula and Brad Penn multi vis in the motor Larry Peto built for my Southwind.

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Why the straight weight? Was it recommended by the engine builder?

28Eliminator said:

Why the straight weight? Was it recommended by the engine builder?

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Yes.
The Whipples on my motors share the oiling system with the engine instead of having a dedicated oil. I went straight weight to help keep pressure up after hard runs.
I had 2 Whipples fail while using a multi vis and a synthetic. Since the switch to Kendall, no problems.

Brad Penn straight 30w, Baldwin B279, Olson oil cooler, 565 TT w/ hv pump.

28Eliminator said:

Why the straight weight? Was it recommended by the engine builder?

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There are lots of variables and opinions.

I like straight weight in most of the engines I build, and I always try to stress proper warm up regardless of engine or oil.

Run whatever the builder recommends. [emoji106]

obnoxious001 said:

There are lots of variables and opinions.

I like straight weight in most of the engines I build, and I always try to stress proper warm up regardless of engine or oil.

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I was hoping you would drop in

Straight weight, even in Hydraulic roller motors?

I'm with you on the proper warm up:thumbup:

28Eliminator said:

I was hoping you would drop in

Straight weight, even in Hydraulic roller motors?

I'm with you on the proper warm up:thumbup:

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Mine is hydraulic roller.

oldschool said:

Mine is hydraulic roller.

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What lifters are running?, spring pressure?

28Eliminator said:

What lifters are running?, spring pressure?

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Comp Cams lifters, I'd have to check my info, but I think the springs are around 175 lbs. at the seat.

Kendall 50W non-synthetic.
Why?
My connecting rod side clearances are opened up just a skoose
Ski racing environments often dictate higher sustained RPMs; TT's build a lot of piston/cyl wall heat
I like oil pressure at idle (hot)
The oil works and lasts; as long as the tune-up is accurate

Bringing this back up because I'm thinking about going to a straight weight instead of the 20-50w I've been running for the last 200 hours or so.

It's always had around 55 lbs at speed, 45 ish at idle when warm. However, after a hard pull, idle pressure will drop to around 30 for a bit. Will I gain anything, or am I wasting my time?

28Eliminator said:

Bringing this back up because I'm thinking about going to a straight weight instead of the 20-50w I've been running for the last 200 hours or so.

It's always had around 55 lbs at speed, 45 ish at idle when warm. However, after a hard pull, idle pressure will drop to around 30 for a bit. Will I gain anything, or am I wasting my time?

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Did you make the switch? Curious myself on using straight 40, especially the VR1

spaniard said:

Did you make the switch? Curious myself on using straight 40, especially the VR1

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No. I wimped out after reading some info on the Morel Lifters I'm running. they recommend a lighter weight oil.

I began adding 1 qt at a time, as it was burning it, I've been adding it. Up to 3 quarts now, and its running smoother now. Been researching, and found others running it without any issues. Changing the oil and going all straight 40

(mercruiser specs call for 25w 40)with the lake being so hot, I dont think we need the VI inhibitors to make it flow any better, since I'm not going to be running it in the winter. With all the added ingredients, on that brand, this will work out better.

28Eliminator said:

No. I wimped out after reading some info on the Morel Lifters I'm running. they recommend a lighter weight oil.

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Morel's ability to pump up and stay pumped up, is extremely sensitive to oil type and weight. The oil viscosity should be determined by the bearing clearance and use.

On a side note: I have been a huge cheerleader for Morel lifters for years. With that said, I will never, ever, use their hydraulic rollers again.

BDMar said:

Morel's ability to pump up and stay pumped up, is extremely sensitive to oil type and weight. The oil viscosity should be determined by the bearing clearance and use.

On a side note: I have been a huge cheerleader for Morel lifters for years. With that said, I will never, ever, use their hydraulic rollers again.

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They were all the rage 5 years ago when i put mine together :rolleyes. I almost sent them back, because they were so tight in the Lifter bores... ended up having to hone all of them to get any clearance :eek

Looked at my build sheet last night... .0024 -.0025 on all the rods. .0026-.0028 mains, rear .0003. Probably a little bigger now after 300 hrs

What say the GURU... 40W or stick with the 20-50?

Straight weight oils stay in grade (don't sheer) better that multi weight offering due to not having any VII(viscosity index improvers). Yes you loose some cold weather pumpability but we aren't exactly boating in 15? temps.

28Eliminator said:

They were all the rage 5 years ago when i put mine together :rolleyes. I almost sent them back, because they were so tight in the Lifter bores... ended up having to hone all of them to get any clearance :eek

Looked at my build sheet last night... .0024 -.0025 on all the rods. .0026-.0028 mains, rear .0003. Probably a little bigger now after 300 hrs

What say the GURU... 40W or stick with the 20-50?

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Stick with the 20/50. Too tight for straight 40 IMO.

I would try the new Merc racing oil. It's 25w-50. It's the oil Mercury Racing calls out from the 525 to the 1650. I've been using it here for a while with great results. Less pressure drop when it gets hot.

BDMar said:

Morel's ability to pump up and stay pumped up, is extremely sensitive to oil type and weight. The oil viscosity should be determined by the bearing clearance and use.

On a side note: I have been a huge cheerleader for Morel lifters for years. With that said, I will never, ever, use their hydraulic rollers again.

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[emoji848]

BDMar said:

Stick with the 20/50. Too tight for straight 40 IMO.

I would try the new Merc racing oil. It's 25w-50. It's the oil Mercury Racing calls out from the 525 to the 1650. I've been using it here for a while with great results. Less pressure drop when it gets hot.

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I'll do that. Thanks Brian!

I should add that for break-in oil we've been using Lucas 20/50 break-in oil with really good results and will continue to break-in our engines with that.

We have used Lucas 20/50 synthetic racing oil after break-in with good results also.

BDMar said:

Stick with the 20/50. Too tight for straight 40 IMO.

I would try the new Merc racing oil. It's 25w-50. It's the oil Mercury Racing calls out from the 525 to the 1650. I've been using it here for a while with great results. Less pressure drop when it gets hot.

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I would like to clarify this statement. What your saying is that a 40 weight oil is thicker than a 50 weight oil???
What I remember is the sequence from lightest to heaviest is 30,40,50. The fist number is just the viscosity inhibitors.
Thanks

spaniard said:

I would like to clarify this statement. What your saying is that a 40 weight oil is thicker than a 50 weight oil???
What I remember is the sequence from lightest to heaviest is 30,40,50. The fist number is just the viscosity inhibitors.
Thanks

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No. I'm saying that 40 is thicker than 20 or 25 when the oil is cold. 20/50 is supposed to flow like a 20 when cold and a 50 when hot.

It's way more complicated than that, but that's the quick and dirty.

spaniard said:

I would like to clarify this statement. What your saying is that a 40 weight oil is thicker than a 50 weight oil???
What I remember is the sequence from lightest to heaviest is 30,40,50. The fist number is just the viscosity inhibitors.
Thanks

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My understanding is that the first number in a multi-visc oil is the cold flow weight of the oil.

BDMar said:

No. I'm saying that 40 is thicker than 20 or 25 when the oil is cold. 20/50 is supposed to flow like a 20 when cold and a 50 when hot.

It's way more complicated than that, but that's the quick and dirty.

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Once you've warmed up your engine, and your running around at optimum temperature, My opinion is, that the 50 weight(20-50) will be much thicker. As it was previously posted, the ambient temperature at the lake is always 100 plus degrees. If you have the setup for high HP springs, lifters etc, then you'd be fine with 50. I noticed 28 Eliminator wanted to go with a lighter weight oil, 20w-50 oil would not be lighter than a 40 weight, hope that helps.

This explains helps explain viscosity and what the first number with the "W"(winter grade) means. The second number is the actual weight of the oil.
http://www.upmpg.com/tech_articles/motoroil_viscosity/

spaniard said:

Once you've warmed up your engine, and your running around at optimum temperature, My opinion is, that the 50 weight(20-50) will be much thicker. As it was previously posted, the ambient temperature at the lake is always 100 plus degrees. If you have the setup for high HP springs, lifters etc, then you'd be fine with 50. I noticed 28 Eliminator wanted to go with a lighter weight oil, 20w-50 oil would not be lighter than a 40 weight, hope that helps.

This explains helps explain viscosity and what the first number with the "W"(winter grade) means. The second number is the actual weight of the oil.
http://www.upmpg.com/tech_articles/motoroil_viscosity/

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You pretty much said what I just said. Except it's based on oil temp not engine temp. And when warm, 50 flows like 50 when its hot, not cold 50, and it doesn't flow like a straight 50 weight. Hot 40w would be fine for David, cold 40w would not. Like I said, it's way more complicated than that and way too much to type. I've had a few meetings with "oil engineers".

This subject for years always get into a debate. Old school train of thought, and new. I'm a believer in learning and following advancements in all aspects of mechanics.

Curious as to what oil to run on a new to me boat. It currently has a Pfaff 588 N/A motor. Not sure about any of the internals.

BLOWN HOWARD said:

Curious as to what oil to run on a new to me boat. It currently has a Pfaff 588 N/A motor. Not sure about any of the internals.

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Pfaff/Baca should have record of it. Call them so you know what you have.

BLOWN HOWARD said:

Curious as to what oil to run on a new to me boat. It currently has a Pfaff 588 N/A motor. Not sure about any of the internals.

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When Paul was there the oil of choice was Torco 20/50

BDMar said:

When Paul was there the oil of choice was Torco 20/50

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I want to say the motor was built around 4-5yrs ago.

Gotta love oil topics, it always makes us see through the media hype, and sales pitches.
Its always best to take the advice of a "Chemical Engineer", so keep posting your results, first hand experience on your ride, is great data logging

Valvoline Racing 20/50.

dexos...0-20W in a 6.2L DI

I just looked at the Mobil 1 web site and it looks like they no longer make the 20W-50 and it has been replaced by 15W-50.

Oil should be chosen by the way the engine is built. One persons good luck of one brand and viscosity really means nothing. The additive package has more to do with the quality of oil than viscosity alone. We have been told that engines need big clearances to keep bearings cool, this is true. You need to know your oil tempeture. Oil tempeture at the bearings can be close to 100 degrees more than what is in the pan, you don't want to melt your bearings.

Other reason for bigger clearance for high hp high rpm engines is crank flex, you need to make sure the crack doesn't flex and take out all of the clearance on the mains. This is where engine build comes in. High quality cranks help here.

For years we have been told you need 10lbs of oil pressure for every 1000 rpm! Why do you need that much oil pressure? You don't. Oil is driven and wedged into the bearing clearance by the cranks journals. If you like unnecessary high oil temps then 80lbs will give you that.

So is there a benefit of low viscosity oil? Tighter bearing clearances with lower viscosity oils helps valve trains get more oil, important for keeping valve springs cool too, and the flow through the bearing doesn't lower.

NASCAR has proven to know how to build engines for reliability. Let's take a engine that runs up to 800 hp at 9000 rpm out of a 358 cubic engine, and does it for 500 miles. On what oil? 0-20 oil. Yes you read that right.

So my opinion on oil. Remember this is just my opinion.

Run a high quality oil that keeps your oil pressure above 25 at idle and max 55 at your max rpm. I had built a 509 with a M3 procharger and was recommended to run a straight 40 weight oil for the procharger, I had 10 lbs at idle and 40 at 5200 rpm, I ran it for about twelve ours that way. My comfort level was a little low, so I went to Mobil 1 15-50 synthetic. Oil pressure went to 40 at idle and 55 at 5200 rpm. Getting 50w oil to the valve train with out a pre-luber is scary. Let your engine cool over night and pull a valve cover off and start engine and see how long it takes to see oil, the only way to understand how long it takes. Oils are unbelievable in quality now, not like when I was a kid.

There is more to engine building than what I have mentioned, and I know we're talking about oil, but we need to know why we choose a viscosity. I just didn't want to get to long and get kicked out of here. Lol

Powermizer said:

NASCAR has proven to know how to build engines for reliability. Let's take a engine that runs up to 800 hp at 9000 rpm out of a 358 cubic engine, and does it for 500 miles. On what oil? 0-20 oil. Yes you read that right.

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Also remember that engine is only built to run like 600 miles and for max HP and fuel efficiency. Boat engines are not set up to run 0W20 that I have seen.

In your pressure sweep example, what you are prescribing may not even be possible for everyone - 25 PSI @ hot idle and 55 PSI at WOT. The one thing you forgot is setup of the oil pump bypass. That also limits the high RPM pressure.

LargeOrangeFont said:

Also remember that engine is only built to run like 600 miles and for max HP and fuel efficiency. Boat engines are not set up to run 0W20 that I have seen.

In your pressure sweep example, what you are prescribing may not even be possible for everyone - 25 PSI @ hot idle and 55 PSI at WOT. The one thing you forgot is setup of the oil pump bypass. That also limits the high RPM pressure.

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I understand what you are saying. I just used those numbers as a safe bet, that if you are in that range you will be fine. As far as engine reliability and time, its all relative. Take a 310hp 454 fuel injected engine, can run over 1000 hrs just with oil changes. Now take a 500hp,525hp, better start thinking about valve spring change around 300 to 400 hrs, depending on use or non use. Of coarse I have seen them go longer and shorter times. But engine run time is all relative.

LargeOrangeFont said:

Also remember that engine is only built to run like 600 miles and for max HP and fuel efficiency. Boat engines are not set up to run 0W20 that I have seen.

In your pressure sweep example, what you are prescribing may not even be possible for everyone - 25 PSI @ hot idle and 55 PSI at WOT. The one thing you forgot is setup of the oil pump bypass. That also limits the high RPM pressure.

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My 6.2 DI L86 requires it!

• All new weight saving aluminum cylinder block casting
• All new cylinder head design with new port shape and valve placement
• Increased compression ratios
• Advanced oiling system - variable displacement pump
• High-strength aluminum alloy pistons
• Oil-jet piston cooling
• Stronger, larger diameter push rods
• High flow intake manifold and electronic throttle
• Iridium tipped, extended life, spark plugs
• 58x crank timing

More reading on the new GM plants http://gmauthority.com/blog/gm/gm-engines/l86/

bocco said:

I just looked at the Mobil 1 web site and it looks like they no longer make the 20W-50 and it has been replaced by 15W-50.

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Oil engineers have a goal of providing less friction loss in an engine, and running lower viscosity numbers are an indication of their success in this field. New car engines are seeing the benefits of those lower viscosity numbers realized in better fuel mileage.

Most new cars are specifying 20W-50 oil, and some have moved to 0W-40. The reduced viscosity oils have proven themselves to be the best choice for the newest engines, and many of them are turbocharged engines that have specific needs for oil that resists breakdown of the long chain molecules.

Oil technology is changing like never before, and it's a good idea to consult your builder regarding the latest API classifications on low viscosity oils. There may be better ideas out there that may change the oil you're running.

rrrr said:

Oil engineers have a goal of providing less friction loss in an engine, and running lower viscosity numbers are an indication of their success in this field. New car engines are seeing the benefits of those lower viscosity numbers realized in better fuel mileage.

Most new cars are specifying 20W-50 oil, and some have moved to 0W-40. The reduced viscosity oils have proven themselves to be the best choice for the newest engines, and many of them are turbocharged engines that have specific needs for oil that resists breakdown of the long chain molecules.

Oil technology is changing like never before, and it's a good idea to consult your builder regarding the latest API classifications on low viscosity oils. There may be better ideas out there that may change the oil you're running.

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I believe the OP was asking for input on what type of oil we used on our Boats for reference. Boat motors differ, since most are built up, i.e heads, cams etc,but not all.

stating your engine type and build along with what oil is being used, will provide a good history report. Although, rarely can we prove an oil caused a bearing to spin, unless the oil was to thin, then this is possible.

I can tell you this on viscosity, being we run in AZ(100 degrees plus ambient temp) and on a boat engine;
The Viscosity Index (VI) of a lubricating fluid refers to how much the viscosity of the oil changes with temperature. A high VI indicates the oil undergoes little viscosity change due to temperature fluctuations, while a low VI indicates a relatively large viscosity change. Oil with a viscosity that does not change much between 40°C and100°C will have a higher VI than an oil with a greater change in viscosity. The Viscosity Index Test (ASTM D 2270) is based on the Kinematic viscosity of the oil at 40°C (104°F) and 100°C (212°F). Viscosity index numbers above 95 are considered high. Oils with a high VI provide more protection to critical components over a wide range of temperatures. Anyone who is ISO 9001 certified an attest to this information, from the hand books.

Assuming you have a mercury engine on your boat, their specs call for a 25W - 40 weight grade oil. I'm curious to see what everyone is using, and how its been holding up over the years. The varying difference are going to the be additives, let keep posting

Interesting topic here. I’ve been road racing, karting, engine building & boating since I was 12 years old. (28 years) I run a spec racer ford 3 in SCCA. It’s a spec SCCA built ford 4 cylinder that we don’t get to touch. If it shits the bed I have to pay SCCA to fix it. I run the Driven oil in it and have had good results. I did break the engine in on conventional oil for the first 20 hours or so. I’ve had a couple of over revs in the 8k range where the the rev limiter is 6,800.

That said I’ve gotten in good with the shop that builds the engines and they say they’ve seen the best dyno #’s with Mobil 1.

They prescribe 5-30 synthetic and warming a cold engine is mandatory before a run. These engines pull all the way up to the redline, in fact you listen for the octave change in the engine at about 6,780 rpm before you shift every time.

Given that we’re using a broad brush when talking about oils I think when discussing which oils weight is right for your application is dependent on wether you have a closed cooling system, fresh water cooling & how well you can control the oil temperature & maintain that heat in the oil between shut offs and restarts.

Running a straight weight thick 40 or 50 weight is good fail safe advice coming from those of us with experience mainly because it’s a fix all for just about every scenario.

Sure you could pick up some more Hp & tq by running a thinner oil in most cases but at what cost? I’d bet you’ll never notice 20 Hp at 5500 rpm in any boat due to the inefficiency of the propulsion systems.

So theres my contribution.

Old thread bump, but anyone running Mobil 1 15/50 still? I know the formula has changed a few times.

Runs2rch said:

Old thread bump, but anyone running Mobil 1 15/50 still? I know the formula has changed a few times.

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No, run vavoline racing 50w, had run it in the past but it depends on the motor like everyone says and the specs...