Mercruiser 4.3l oil

[OVERKILL]

Ummmm ... very good point about the slip but would disagree to suggest or maybe imply a marine engine has the same load as a vehicle with wheels if I am understanding your post. But I think you maybe suggesting physical bogging down of the engine by improper propeller, vs the high load of pushing a barge (boat) through water. MeCruiser does note the tremendous load marine engines are under.
Oil temps will run far hotter, also taking into account the high RPMs and huge gas consumption compared to a car..

Also the 2,000 lb weight you mention is too light, A 21ft Chaparral from the factory with this engine weighs in at 3,100 lbs dry weight.
Throw in a full tank of gas 240 lbs, plus the boat has a passenger capacity of 1,600 lbs. You can be pushing close to 5000 lbs.

These engines are also used in twin configurations for boats weighing twice the dry weight mentioned above.

"Back in the day" a good friend of mine had a cabin cruiser with a 4.3L, think it was at least 25', similar to this one:

$10,000 25 ft Bayliner Capri Custom Cabin Cruiser Menlo Park

The "Orca One" is a modern 1992, well maintained,

www.allboatlistings.com

And it's gotta be at least 5,000lbs.

 

[MacManus99]

Disagree. Prop will slip long before you bog the motor with load, even a Bravo 4 blade SS 14.5x19 pitch, with the exhaust holes fully closed, will slip before a 4.3 gets loaded down. You might be able to load one with a 3 blade 21 pitch, but that is probably not the correct prop for your boat if it has a 4.3 motor.
You don't "load" 4.3s, they come in boats that weigh 2K and 21 ft or less.

I will agree with you that there is always some amount of prop slip, but when the transmission is in gear, a marine engine is darn near always under more load than it would be in a car.
A car engine may see significant loading when accelerating hard up a hill, but otherwise it is comparably unloaded. Even under light acceleration, it doesn't compare to a boat maintaining speed underway. This is why boats can see elevated oil temps, even when the coolant in the block is dead steady at 160°.

 

[wpod]

People have a hard time grasping engine load and oil temperature .

 

[PontiacHO]

Just on plane RPMs for a boat/marine engine is probably the no load scenario if your comparing the same with a car at moderate steady cruise speed. The marine engine will be 3,000+ RPMs whereas the car will be substantially less at 1,400 to 1,800 RPMs. Marine engines work harder to achieve like situations. 4.3 V-6 will use more fuel than a 5.0 V-8 in the same boat/hull/weight configuration.

 

[Nola_mike]

Just on plane RPMs for a boat/marine engine is probably the no load scenario if your comparing the same with a car at moderate steady cruise speed. The marine engine will be 3,000+ RPMs whereas the car will be substantially less at 1,400 to 1,800 RPMs. Marine engines work harder to achieve like situations. 4.3 V-6 will use more fuel than a 5.0 V-8 in the same boat/hull/weight configuration.

Still way more load on the marine engine. The equivalent would be going up a mountain in 5th gear towing a trailer constantly. Not sure where you get your fuel economy info

 

[Nola_mike]

Well, just rereading the manual. It specifically recommends 20w-40 over 20w-50, and (interestingly) specifically recommends against synthetic.

 

[PontiacHO]

Still way more load on the marine engine. The equivalent would be going up a mountain in 5th gear towing a trailer constantly. Not sure where you get your fuel economy info

Been around a lot of boat owners comparing fuel usage. The 4.3 works harder to stay on plane than the 5.0 in the same size/weight boat. Sure, idling around may be different but as stated—-on plane.

 

[MacManus99]

Been around a lot of boat owners comparing fuel usage. The 4.3 works harder to stay on plane than the 5.0 in the same size/weight boat. Sure, idling around may be different but as stated—-on plane.

I've read second-hand accounts similar to this. Very common for people to swap a small block V8 in place of the 4.3L. The fact that a scrapyard automotive 305/350 is likely easier to find and cheaper probably has something to do with it as well.

I'm not trashing the 4.3, either, as I think they're great boat engines. Just heard and read similar accounts.

 

[alarmguy]

Well, just rereading the manual. It specifically recommends 20w-40 over 20w-50, and (interestingly) specifically recommends against synthetic.

Yup, manual is best. The Quicksilver 20/40 is really a straight weight 40 to the best of my knowledge. Quicksilver states there are no viscosity improvers to break down. (something to that affect)
Some people do not like the price and get an automotive 20/50 which will most likely end up like a 40 anyway.
Im one for following the manual though when possible. I remember a a long time ago my brother had twin engine V6's SeaRay in a 28 Foot Searay.
He always used Quicksilver 20/40 as I did too, actually only changed a few years ago when I no longer had a Merc and now Volvo.
One year he thought he would try just regular Castrol 20/50 because it was so much cheaper. One must know, my brother was on the water almost every sunny day of his life and knew his boats well. Also one to change his own starters, exhaust manifolds bolt on stuff like that, We also both pulled our outdrives every winter and serviced them.
Anyway, after a long hard run from the Ocean, through Jones Inlet to his back yard, I never forgot how he told me, never again, he got back to the dock and his valves were clattering away. This never happened to him with the Quicksilver and he has put thousands of hours on boats over his lifetime and that one I mentioned I think it was over 2000 hours and knew it inside and out.

Im not doing an ad for Quicksilver just stating something that happened.

 

[dlundblad]

"Back in the day" a good friend of mine had a cabin cruiser with a 4.3L, think it was at least 25', similar to this one:

$10,000 25 ft Bayliner Capri Custom Cabin Cruiser Menlo Park

The "Orca One" is a modern 1992, well maintained,

www.allboatlistings.com

And it's gotta be at least 5,000lbs.

Sounds like a speed demon. Lol

 

[OVERKILL]

Sounds like a speed demon. Lol

How hard that thing worked to get up on plane? oh man, first time I was out in it, I was surprised it did! Couldn't believe it had a V6 in it, I expected a 350 or 351W at minimum, if not a 454/460.

 

[dlundblad]

How hard that thing worked to get up on plane? oh man, first time I was out in it, I was surprised it did! Couldn't believe it had a V6 in it, I expected a 350 or 351W at minimum, if not a 454/460.

Ive been pulled behind a 17’ Bayliner with a 4.3 in a tube. That left me disappointed.

 

[OVERKILL]

Ive been pulled behind a 17’ Bayliner with a 4.3 in a tube. That left me disappointed.

Pretty sure our Supra could pull our old Glastron with a GM 4-pot and the tube faster than the Glastron was capable of going, lol

 

[alarmguy]

"Back in the day" a good friend of mine had a cabin cruiser with a 4.3L, think it was at least 25', similar to this one:

$10,000 25 ft Bayliner Capri Custom Cabin Cruiser Menlo Park

The "Orca One" is a modern 1992, well maintained,

www.allboatlistings.com

And it's gotta be at least 5,000lbs.

Yes, I remember those boats well, at the time it was a value competitor to SeaRay Sundancer. It gave you a lot for the money and got you on the water with all the needed features of a small cabin cruiser.
Im not sure if this was during his time and Im losing track of how long ago.

As the stern drive competition was heating up with OMC Cobra Drives, Mercruisers and I am not sure but think Volvo.
Brunswick to preserve market share started buying the boat manufacturers themselves of which Searay and Bayliner ended up being both owned by the same parent, Brunswick. OMC at the time was buying up other boat makers.`
I feel (and I could be wrong) Searay legendary quality took a small hit (most likely for more profit) and Bayliners less then stellar reputation improved a little bit. (most likely do to better quality control and economy of scale)
The Bayliners at the time would take a beating in the Salt Water, I am in no way saying they were bad, just more value that allowed people to get more boat for their money at a cost of lets say chrome plated hardware vs Stainless, stuff like that.
For the most part we had a lot of Sea Rays in the family back then though I was REALLY tempted by what I think at the time was a Bayliner 24 or 22 (something like that) Express. I loved the idea of the simplicity of a large boat and one I can upgrade myself. It was a bargain price too and got good reviews.
I do miss those boating magazines too, Like "Trailer Boats Magazine" and whatever else.

 

[LouC]

I've done 2 oil analyses on my 1988 4.3 run on the Mercruiser/Quicksilver 25/40 conventional oil and both times the oil viscosity held up very well, better than expected, both times it was above the upper limits for a 40 wt.
2015:
SUS vis @ 210*F=81.1, cSt vis @100*C=15.79
2021
SUS vis @210*F=16.54, cSt vis @100*C=16.54

This engine is in a heavy (4200 lbs) 20' boat so it doesn't have a light load to propel, I compensate for the weight with a lower pitch prop (15.5x15) lowers top speed but also lowers load on the engine.
So if you want an oil that doesn't shear down in marine use, this one seems to work.

 

[alarmguy]

I've done 2 oil analyses on my 1988 4.3 run on the Mercruiser/Quicksilver 25/40 conventional oil and both times the oil viscosity held up very well, better than expected, both times it was above the upper limits for a 40 wt.
2015:
SUS vis @ 210*F=81.1, cSt vis @100*C=15.79
2021
SUS vis @210*F=16.54, cSt vis @100*C=16.54

This engine is in a heavy (4200 lbs) 20' boat so it doesn't have a light load to propel, I compensate for the weight with a lower pitch prop (15.5x15) lowers top speed but also lowers load on the engine.
So if you want an oil that doesn't shear down in marine use, this one seems to work.

Very cool seeing Long Island.
If you haven't followed my posts, I spent 40 or so years (including childhood) boating the on the Great South Bay and Jones as well as Fire Island inlets. For me personally, there is no place like it and the only thing I miss up there. So many good times though true, we can say that about the past in a lot of things.

 

[Nola_mike]

I've done 2 oil analyses on my 1988 4.3 run on the Mercruiser/Quicksilver 25/40 conventional oil and both times the oil viscosity held up very well, better than expected, both times it was above the upper limits for a 40 wt.
2015:
SUS vis @ 210*F=81.1, cSt vis @100*C=15.79
2021
SUS vis @210*F=16.54, cSt vis @100*C=16.54

This engine is in a heavy (4200 lbs) 20' boat so it doesn't have a light load to propel, I compensate for the weight with a lower pitch prop (15.5x15) lowers top speed but also lowers load on the engine.
So if you want an oil that doesn't shear down in marine use, this one seems to work.

Hi @LouC , you stalking me over here?

 

[LouC]

Lol
the man who successfully negotiated the 4.3 swap, detail by detail!
I just got back my 3rd Oil analysis on the old 4.3.
On the first, done in 2011, I had high wear metals for iron, aluminum & lead, and sodium showed up in the oil. Then, I was using Delo 40 straight weight. Didn't think of pulling the heads to take care of it then. Had a bad overheat in 2013, but engine ran fine next 2 seasons.
On the second done in 2015, I had high wear metals for aluminum & iron again, and sodium in the oil, so I knew this was eventually going to have be dealt with.....
In 2016 the head gaskets started leaking and put some water in a cyl and oil, as I posted on iboats I rolled the dice and replaced the head gaskets & installed reman cyl heads
The third, that was from last fall, showed normal for everything except iron still slightly elevated but not bad. No more concern with sodium in the oil so those Fel/Pro marine head gaskets did their job. Everything else normal and the Merc oil tests out as a high 40 wt viscosity.
When I winterize it this week I'll pull anothe sample and do a compression test.
Thinking of changing to Quicksilver 25/50 syn blend. Expensive, but the most protection.

 

[LouC]

Very cool seeing Long Island.
If you haven't followed my posts, I spent 40 or so years (including childhood) boating the on the Great South Bay and Jones as well as Fire Island inlets. For me personally, there is no place like it and the only thing I miss up there. So many good times though true, we can say that about the past in a lot of things.

We do our boating up on the North Shore but do 4 wheeling on the South Shore beaches.

Eatons Neck Long Island looking across the Sound to Connecticut...

 

[alarmguy]

We do our boating up on the North Shore but do 4 wheeling on the South Shore beaches.
View attachment 122363
Eatons Neck Long Island looking across the Sound to Connecticut...

Very nice, there is two areas of the Long Island sound that I know.
One would be Moriches inlet where my dad used to take us mackerel fishing and the other very good memories of Sound Beach in Wading River when young we would fish there often, my dad had a light boat with outboard that we would launch on Sound Beach.
I remember trolling between the giant flat rocks and also there used to be a big wreck in the sand a little ways from the beach.

From what I remember the electric boat works that build military submarines was on the Connecticut side and we used to see the periscopes and sometimes the submarines. I also remember vaguely the navigation charts that my father had and there was an area on the map that said do not enter military zone or something like that.

Do I remember correctly that Eatons Neck had coast guard weather reports, all I know is I know the name well.
Ahhh the beaches, when young my fire d has a 4 wheel drive jeep, we would “fish@ and party all night in and around Gilgo and the “Sore Thumb” of Fire Island Inlet