Marine engine oil discussion

[NHHEMI]

Originally Posted By: cchase

I can't help but notice he has a few of the "typical" misconceptions about motor oil. One that caught my attention was "20w50" being "20 weight in winter" and "50 weight at temperature".


That is actually how multi viscosity oils are rated. The ##W is cold viscosity and is often referred to as the "winter weight". The -## is the viscosity at operating temperature. So a 20W-50 is a 20 weight oil when it is cold and a 50 weight when the engine has reached operating temp. A 5W-50 would be a 5 weight when cold but still a 50 weight at operating temp the same as a 20W-50.

0W-30, 5W-30, 10W-30 are all 30 weight oils at operating temp. 0W-40, 5W-40, 10W-40, and 15W-40 are also all 40 weights at operating temp. The cold or winter weight is what varies.

Your friend is correct.

 

[cchase]

Originally Posted By: NHHEMI
Originally Posted By: cchase

I can't help but notice he has a few of the "typical" misconceptions about motor oil. One that caught my attention was "20w50" being "20 weight in winter" and "50 weight at temperature".


That is actually how multi viscosity oils are rated. The ##W is cold viscosity and is often referred to as the "winter weight". The -## is the viscosity at operating temperature. So a 20W-50 is a 20 weight oil when it is cold and a 50 weight when the engine has reached operating temp. A 5W-50 would be a 5 weight when cold but still a 50 weight at operating temp the same as a 20W-50.

0W-30, 5W-30, 10W-30 are all 30 weight oils at operating temp. 0W-40, 5W-40, 10W-40, and 15W-40 are also all 40 weights at operating temp. The cold or winter weight is what varies.

Your friend is correct.


My problem is that his reference implies that "20 weight" and "50 weight" are the same units. They are most certainly not.

 

[NHHEMI]

Sorry but you have completely lost me?

 

[cchase]

Originally Posted By: NHHEMI
Sorry but you have completely lost me?


His words were:

Quote:
Another additive known as a viscosity improver attaches to these guys, and helps them to thicken as the temperature goes up. This is how 20W-50 oil can act as a 20 weight in winter and a 50 weight as temperatures elevate.


a 20W50 as we on here all know is not "thicker" at high temperatures. He mistakenly believes that a 20W50 is "20 weight" when cold and "50 weight" when hot. As we know, the 20W is not a measure of kinematic viscosity as the "50" is, and therefore the numbers are not the same units, as he implies.

Make sense now?

 

[miker1]

Amsoil has not discontinued their marine 30w oil. Also as everyone on this forum knows lots of people have used diesel oils in auto and motorcycle applications with no problems. Modern diesel oils do not have high zinc levels. Some of his "facts" do not add up.

 

[NHHEMI]

Originally Posted By: cchase
Originally Posted By: NHHEMI
Sorry but you have completely lost me?


His words were:

Quote:
Another additive known as a viscosity improver attaches to these guys, and helps them to thicken as the temperature goes up. This is how 20W-50 oil can act as a 20 weight in winter and a 50 weight as temperatures elevate.


a 20W50 as we on here all know is not "thicker" at high temperatures. He mistakenly believes that a 20W50 is "20 weight" when cold and "50 weight" when hot. As we know, the 20W is not a measure of kinematic viscosity as the "50" is, and therefore the numbers are not the same units, as he implies.

Make sense now?

Thanks.

 

[FowVay]

Mr. Wingnut seems to be of the impression that PAO base fluids are ester based also. He's just another guy that has a fascination with boats and oil. Not all-knowing but entertaining none the less. We can all learn something from everybody.

 

[Steve S]

Originally Posted By: FL_Rob
we need to make Wingnut a member over here! I read the entire page ...VERY interesting!
With that article and oil 101 this site would be the best informed site on the net.

 

[bullwinkle]

I had read that only high RPM racing gas engines had problems with high ZDDP oils causing detonation/preignition, and I've also heard that full syn oils (both in the engine and lower unit) have poor moisture handling characteristics-is wingnut right or are the other guys right??

 

[lars11]

But still, lots of people here insist on associating the winter pumpability number with the viscosity number just because they are printed close to each other on bottles.

 

[Pete591]

When I was in Miami at the offshore boat Poker Runs I was surprised to see how many boats running Mobil-1 20W050 V-Twin Motorcycle Oil. Most have Cigarette boats costing on average $300-500,000.

Their builders open the engines up for a refresh and they all say you can eat off the the thing. Valves look great. Most would not switch.

These are Mercury HP engines rated at 525HP to 1150 HP.

Wix filters are very common.

I was amazed.

 

[coupza]

Great debate! I would love to hear your opinion on my new to me 1989 omc 4.3 v6. Calls for SAE30 but all the oil I can find specifies it is designed for diesel engines. Should I use it anyway or go to one of these multigrade oils discussed in Wingnuts forum. Also wondering if I should go synthetic or not. I am in Alberta Canada and the boat will primarily be used for family fun 65 to 90+ degrees F.

 

[Donald]

Originally Posted By: SteveSRT8
I can assure you that in the case of GM motors used in most domestic boats the clearances are exactly as any other. Matter of fact, there are no internal differences at all.

The term "marine" as used for boats just means more money!


You are incorrect. The GM 5.7L engine used in many Mercruiser I/Os is a 4 bolt main. Most of the same engine in cars, etc. are 2 bolt main. Some heavy duty truck engines may be 4 bolt main. You would be tossing your money away if you used the lighter duty version in a boat. The engines are run in a constant RPM mode, which is not how a car or truck is run.

 

[Ken2]

Quote:
Calls for SAE30 but all the oil I can find specifies it is designed for diesel engines.
Many straight 30 wt oils are dual rated for both diesel and gasoline engines. You can find with with the "C-" commercial rating for diesel and the "S-" service rating for gasoline engines. Chevron Delo 400 SAE 30 is just one example. Chevron Delo 400 10W-30 would be a good choice for a multi-grade, as would other brands of dual diesel/gasoline rated 10W-30. These dual rated oils have a more robust additive package than auto oils designed for modern car engines. No real reason for you to use synthetic unless you want to extend your oil drain interval.

 

[seadancer]

I'm new to this group, so bear with me. I have a 1972 uniflight with 2 chrysler 318's rebuilt in 2009. have 100 hrs on them. I'm using rotella 15w40 oil. with the older engine (flat tappets),do I need to use ZINC additive, like LUCAS engine break-in oil additive? Should I be changing over to synthetic oil with the older rngine?

 

[Bror Jace]

"Many straight 30 wt oils are dual rated for both diesel and gasoline engines. You can find with with the "C-" commercial rating for diesel and the "S-" service rating for gasoline engines. Chevron Delo 400 SAE 30 is just one example. Chevron Delo 400 10W-30 would be a good choice for a multi-grade, as would other brands of dual diesel/gasoline rated 10W-30. These dual rated oils have a more robust additive package than auto oils designed for modern car engines. No real reason for you to use synthetic unless you want to extend your oil drain interval."

+1

seadancer, you might want to read Ken2's response a couple of times.

You are already using a pretty good oil for marine engines. If your oil intervals are on the short side (hours, not months) then I bet you are fine as is.

If your use is severe or you tend to extend your oil change intervals (for whatever reason) an extra zinc additive might be good insurance. Lucas makes one, Red Line Oil makes one (they market it for break-in) and Schaeffers makes a great supplement I have used in the past and UOAs have shown it seems to help:

http://www.schaefferoil.com/engine-oil-treatment.html

Knowing a little more about how you run your boat would help members here. Also, if you want hard evidence one way or the other, you could do a used oil analysis (UOA) on a sample of used oil to see how it held up, how much wear you are getting, etc ...

 

[BUBBA0420]

Bror: The "C" does not stand for Commercial it stands for
Compression Ignition

 

[Pablo]

Originally Posted By: miker1
Amsoil has not discontinued their marine 30w oil.


I saw that gem. Just seems like a guy on the internet. Some things OK, some things wrong. I wasn't that impressed. Some marine oils are actually made for professional use in marine conditions 24x7x365.

 

[Bror Jace]

BUBBA0420, yes, I know that. The passage in italics was quoting Ken2's post which was pretty good despite that minor error.

Ignition Types:
S = spark
C = compression.

 

[bullwinkle]

Originally Posted By: Donald
Originally Posted By: SteveSRT8
I can assure you that in the case of GM motors used in most domestic boats the clearances are exactly as any other. Matter of fact, there are no internal differences at all.

The term "marine" as used for boats just means more money!


You are incorrect. The GM 5.7L engine used in many Mercruiser I/Os is a 4 bolt main. Most of the same engine in cars, etc. are 2 bolt main. Some heavy duty truck engines may be 4 bolt main. You would be tossing your money away if you used the lighter duty version in a boat. The engines are run in a constant RPM mode, which is not how a car or truck is run.
Actually, most GM truck 5.7/350 motors are 4-bolt main blocks. Considering I've personally known guys who've run unmodded SB Chevy motors in excess of 7K @ the track (usually 327s), and my brother has run 400 small block Chevies in his dirt track car for many years, 2-bolt main blocks, I would think a boat could handle a 2-bolt main block OK. I would think the factory (usually) nodular iron crank would fail before the block did.