50:1 / 40:1

[Jim_Pat]

If you run a mix that is 40:1 does that do the same as fatting it up? Or is 40:1 too lean on oil to run on a lake pleasure/performance boat? Just trying to learn the 2 cycle world. V6 OMC loopers 225's

Thanks

Jim

[kimswang]

50:1 if you have the VRO disconnected for normal use. For high performance OMC recommends 25:1 without the VRO.

[imq707s]

If you run a mix that is 40:1 does that do the same as fatting it up? Or is 40:1 too lean on oil to run on a lake pleasure/performance boat? Just trying to learn the 2 cycle world. V6 OMC loopers 225's

Thanks

Jim

50:1 is going to have less oil in it than 40:1 (40 parts gas, 1 part oil).

If I know I'm just going to be cruising around the lake with a bunch of people in the boat, I will mix 50:1. It smokes a little less, and doesn't load up if I'm going to be idleing around for long periods of time. If I'm going to be out screaming around the lake, or at least running harder than normal...I will mix 40:1 in order to get a little extra lubrication in the fuel.

[terry taylor]

Split the difference 45 to 1.

[JohnR]

If you run a mix that is 40:1 does that do the same as fatting it up?

Running more oil in a premix situation actually leans out the air/fuel ratio. More oil in the mix means less fuel and more oil going through the carb.

John

[Jim_Pat]

Thanks for all the help, so I'm assuming that when you run double oil on break in that is a 25:1 mix?

[imq707s]

Thanks for all the help, so I'm assuming that when you run double oil on break in that is a 25:1 mix?

Yep..you got it :thumbsup:

[Forkin' Crazy]

Running more oil in a premix situation actually leans out the air/fuel ratio. More oil in the mix means less fuel and more oil going through the carb.

John

No it does not, unless it is an extreme amount.

[racer]

Forkin, Actually John is right but the amount is so little you cant generally tell. When you have less fuel carried in by the same amount of air the ratio changes. The oil also burns a bit hotter than fuel. The difference is so little most dont even think about it but if you have an engine right on the edge it can make a difference. The other side is not all fuel has the same pacific gravity so different amounts can be pulled the the pick up tube in the carb, again it is minimal, oil also changes this.

[kimswang]

Thanks for all the help, so I'm assuming that when you run double oil on break in that is a 25:1 mix?
Without VRO, yes.

[Tom Foley]

Don't forget that one of the major functions of oil is COOLING . The oil aids in cooling engine parts as well as lubricity . Besides the smoke more oil does not do any real harm in our outboards , especially if it is TCW- 3 rated . No expert ..but this works . I run 32:1 myself in the 260's , thats just me , everyone has their preference based on experience .

[powerabout]

more oil makes more power as well down to abouit 20:1

[imq707s]

more oil makes more power as well down to abouit 20:1

How? Why?

[terry taylor]

Largely depends how your using an engine and oil quality. Running rich oil mix can create power robing carbon build up and foul plugs, and looks down right embarrassing at times

[JohnR]

I would guess less friction.

[allstock]

How? Why?

Better ring sealing is what I was told.

[Forkin' Crazy]

Forkin, Actually John is right but the amount is so little you cant generally tell. When you have less fuel carried in by the same amount of air the ratio changes. The oil also burns a bit hotter than fuel. The difference is so little most dont even think about it but if you have an engine right on the edge it can make a difference. The other side is not all fuel has the same pacific gravity so different amounts can be pulled the the pick up tube in the carb, again it is minimal, oil also changes this.

Well I guess there's your answer, although many would disagree (where are they now? :nonod: ).

FYI the search function seems to be working now. A lot of discussion on this subject if you look for it.

I'm out on this one, y'all can have it! :)

[powerabout]

your replacing fuel with oil
therefore there is less fuel per unit air going down the hole.

Although how the oil burns versus fuel is a whole other subject and I'd bet thats different for every oil and how would you test that?
With one of those octane testing engines?
run it through a diesel as see what happens?
anybody

[JohnR]

I know that back when they ran 2 stroke engines in the supercross and motocross series' the mechanics would fine tune the jetting by playing with fuel to oil ratios. I agree that it makes little difference in the actual AF ratio but calling it richer when adding oil is a misnomer.

John

[bluess02]

Ok I am curious of this as well. I want to go to premix mainly becasue i want to go to an electric fuel pump set-up. I am running 2.7 heads and boyeson reeds on a 2001 250 johnny, would this be considered high performance? I am running this on a 25 fountain sportfish center console, can i run 50:1 premix or should i run 40:1? I do alot of raft-ups and dont want to be cruising around no wake areas with a cloud following me if I can at all help it.

[imq707s]

I have a GT-200 Looper with 2.7 heads. I always run 40:1.....but I have tried 50:1.....and I don't notice any less smoke. Run 40:1....it's not going to puke smoke everywhere :) I can idle around all day..and I've never had a problem with excessive smoke or fouling any plugs.

[Lockjaw]

Someone with a dyno needs to do a test, see which oil "adds" the most hp as ratios change.

[JohnR]

I know there was a guy on one of the 250R boards that did a bunch of dyno testing with different oils and at different ratios and I believe he found that more oil made more power but like someone else here said, when you start to get crazy with it you end up with problems.

As far as smoke, I think it has a lot to do with the brand/quality of the oil. I ran Supertech for a tankful or two and it smoked a hell of a lot more than the Pennzoil XLF I'm using now. The motor is oil injected so the ratio didn't change between the two.

John

[perfmarine1]

If you read the manual OMC states any stock outboard used for hi performance use they recomend 25-1 ratio. If you are running VRO you add 50-1 in the tank not just for break in. They mention nothing about changing jets when using twice the oil so makes little or no difference. I believe its the Gas that carbons up the motor not the oil. Here is why. In 78 I bought a new 235 & Vulture in 1980 it burnt a piston. Tore it down and nearly all rings were stuck to piston.50-1 Evinrude oil.People told me its the oil. So rebult it and used Amsoil 100-1 oil. In 2 years tore it down and yep stuck rings again.This was near the time they came out with TCW-3 oil that has the solvent to clean the carbon build up. So the factories found this out also. Now granted big cross flows are notoris for sticking rings. So good motors for test. In the late 80's I modified a pair of 300's for a customer and when tore down I could not believe how clean his motors were inside. He was running merc prem plus. Since then I used that oil plus Yamaha ring free and have had no problems sticking rings. Also Jay Smith has stated penzoil prem plus runs clean and smokes less and I am sure you can believe him. Also some racing oils do not have this solvent in them,that you can smell,and are designed for motors that are tore down on a regular basis. Just my 2cents

[bluess02]

Ok with that said , I'm using pennzoil xlf right now, and i was told quicksilver is a no no on OMC...... so whats the best, least smoking good for my motor happy medium??

[JohnR]

I've been happy with XLF in my OMC. As much as I hate going there, WalMart had it for $11 a gallon the last time I was there. I think it was some kind of close out, I bought the 4 they had left. :)

[perfmarine1]

You were told wrong, quik and merc are the same I am sure as long as prem. plus. I dont know what is in the XLF oil that it is for seasoned motors,it prob has a additive to help swell seals in older motors. I would switch to penz prem plus or merc prem plus IMO. The BRP oil prob has improved a lot from years ago I just have no tried IT. I am sticking with what I know works.

[ChrisCarsonMarine]

Jim...Pat,your post has been pummeled with opinions,so,in my opinion for stock/sport use with your motoe i would per-mix at 50:1,i like the pennzoil blend,it seems to be a fine oil.The term'fattening up' refers to fuel/air ratio and means adding more fuel,and dosen't relate to fuel/oil mixture at all.Now for facts,not opinions...50:1 is 2 % oil,98% gasoline,whereas 25:1 is 4% oil,96% gasoline.What is hard to understand,less gasoline is leaner,not to mention thicker,and thereby slower through the jets,theoretically.Racers comment is right on,the difference in mixture is there,and in most cases unnoticed,unless the motor is on the verge of leaning out and gets pushed over the edge by a small effort,Chris

[bigbore]

50:1 is going to have less oil in it than 40:1 (40 parts gas, 1 part oil).

If i know i'm just going to be cruising around the lake with a bunch of people in the boat, i will mix 50:1. It smokes a little less, and doesn't load up if i'm going to be idleing around for long periods of time. If i'm going to be out screaming around the lake, or at least running harder than normal...i will mix 40:1 in order to get a little extra lubrication in the fuel.
perfect

[perfmarine1]

Jim...Pat,your post has been pummeled with opinions,so,in my opinion for stock/sport use with your motoe i would per-mix at 50:1,i like the pennzoil blend,it seems to be a fine oil.The term'fattening up' refers to fuel/air ratio and means adding more fuel,and dosen't relate to fuel/oil mixture at all.Now for facts,not opinions...50:1 is 2 % oil,98% gasoline,whereas 25:1 is 4% oil,96% gasoline.What is hard to understand,less gasoline is leaner,not to mention thicker,and thereby slower through the jets,theoretically.Racers comment is right on,the difference in mixture is there,and in most cases unnoticed,unless the motor is on the verge of leaning out and gets pushed over the edge by a small effort,Chris


Good point Chris, so there you all go, even twice as much oil and you are still dealing with 96% gasoline. So the difference between 50-1 & 40-1 will make no difference in jetting, only on paper. If you were jetted that close you would have to change jetting from spring to summer and back for fall,because of air density changes, that can have a 200-400rpm difference on carb outboards,that may have a greater affect on jetting than the oil issue more so up north than down south I would think.

[Lockjaw]

I can tell you with certainly that BRP XD100 has to be the cleanest burning oil I have ever run. Even the inside of your prop stays clean. You don't need to decarb when you run it.

[perfmarine1]

It should be at 45.99 per gallon, recomended for etech's with proper programing only.

[Lockjaw]

You can get it online much cheaper then that. I think Dusky's has it for 32 bucks a gallon. I ran it in my motor for a couple years, then changed over to blue marble. THink the XD100 is better oil though. Even my 2 stroke lawn equipment ran like a top with it. Never ever had the crank it up and listen to it sputter for a couple minutes until the jets cleared out.

I think I am going to get some and just add it into my gas to help keep things clean.