Fuel/Oil Mixture

[Fishin_Dan]

Hey guys, I'm sure this has been covered here before, but couldn't find it with the search...

Just curious as to what mixture everyone uses of oil & fuel. I have a 2 stroke evenrude, and was told that for every 20L of fuel, to add 400ml of oil... Well I did this yesterday on its maiden voyage, and she ran well for a while, but then it all went REALLY pear shaped! It seems like (From my limited knowledge) that the mixture was too oil rich, and it just clogged the carby up. The back of the oil container (Castrol) says to mix at 100:1, which means I shouldve only put in 200mls...

What do you guys mix too?

[mini696]

I used to mix to 25:1 which means for every litre of fuel I put in I need 40ml of oil. So in your case I would have put in 800ml of oil. I have changed to 40:1 (25ml per litre) because I blow a bit (only a little) of smoke when its hot and at idle.

I own an old (18 years) Evinrude 25HP. I haven't had any problems with too much oil. But I do have plugs which are rated hotter than standard, it is common to have hotter plugs on these motors.

[Fishin_Dan]

I used to mix to 25:1 #which means for every litre of fuel I put in I need 40ml of oil. #So in your case I would have put in 800ml of oil. #I have changed to 40:1 (25ml per litre) because I blow a bit (only a little) of smoke when its hot and at idle.
25:1! That's a lot more than what I had mixed! Hmmm... Maybe it's not oil mixture then ??? :'( Does anyone know what the symptoms could mean? (Rough at low speed, runs ok at high speed, hard to start, etc)


But I do have plugs which are rated hotter than standard, it is common to have hotter plugs on these motors.
Did you put these in yourself? What's the difference between them and the standards? Just better quality?

I don't know much about outboards, so am a little confused.

Cheers, Dan

[Rowdy_2002]

Gday Dan,

You said it was the maiden voyage. I am assuming that it is a secondhand rig. Was there any fuel left in the tank before you filled her up?

If there was fuel in here it may have been either old or contaminated. Fuel that has been mixed with oil tends to go off quicker than straight petrol.

You need to mix the oil at the rate that the engine manufacturer specifies and use the grade of oil they specifiy as well.

A lot of the newer motors will run with 100/1 fuel oil ratio but the older ones in most cases don't, so be careful or else it could get expensive.

Greg

[jimbamb]

Yep,do as rowdy says.use reccommended oil mix,maybee a little more oil if ya a little wary.I found my mower doesnt like 100 to 1 mix as it is reccomended at 25 to 1.and i used fuel out of the boat at 100 to 1......,its true. the older ya get the sillier ya get.. in my case anyway.

[Fishin_Dan]

Hey Greg. Yep is a second hand boat, and it is an older motor. Fuel tank was empty before I filled both (1 old tank came with boat, 1 brand new tank) from scratch.

A few people I know run 50:1, so I wasnt sure if that was it....

I guess she's gonna have to go for a service... Anyone recommend someone on Brisbane Northside???

[PG]

Formy money I'd take it to get a service done. The mechanic will most likely change the water pump impellor, spark plugs, gearbox oil, lubricate joints, check the electrics and god knows what else !
All of the above will have an effect on how well it runs and while you're there, ask what mix you should use. I doubt there's a mechanic out there who wouldn't give you an honest opinion on the mix and maintenance. It may cost a bit on first check-up but money wll spent if it saves you from being stuck in the middle of the ocean !
Don't be afraid to ask questions.
Your problem could be any one of the above or a combination of any number of them to some extent.
Good luck :)

[Fishin_Dan]

I went into Northside Marine yesterday arvo, and spoke to the guys in there. According to them, the mix I used wouldn't have caused an issue. The guy said it is more likely some crap was in the bottom of the fuel tank that has blocked it all up, but he didn't want to say what it "could be" too much before he actually looked at it. Kind of frustrating in a way, but I guess that is a good thing.... Unfortunately they couldn't do it before the New Year, so I may be out of action for a few weeks... :( On the upside, I got my Ausfish stickers delivered yesterday, so they will be going on soon! ;D

[Wezza]

Hey Dan,
Ring around. I managed to get mine serviced this week. Im sure someone might be able to get you in before chrissy.

[Oldyella]

Check here...
http://archive.bibalex.org/web/20010801165541/goa-northcoastoil.com/tips/obmixing.html

Most OB's are 50:1
You need to know exactly what that year Jonnyrude was designed to run with.Too rich will cause a carbon build up and too lean can cause a #meltdown.
My 2cents.. Keep your fuel fresh (No more than 8 weeks) and add fuel stabiliser. Install a car inline fuel filter to ensure that only clean fuel is delivered.

[Wezza]

Hey, I just checked out that site and it is a bit confusing. I have a Merc 80 and it has the following.

2.5,3.3,4,5,6,8,9.9,15,20,25,30,40,50,60,60 Bigfoot,75,90,100,115,125,135,135Optimax,150, 50 EFI,150 Optimax,175,175 EFI,200,200 EFI, 200 Optimax,225,225 EFI,225Optimax,250 EFI
With oil injection or Auto Blend All —1
Without oil injection or Auto Blend All 50:12
1 First tank full 50:1.
2 First tank full 25:1.

So what is it???? 50:1 or 25:1???? I Thinks I stick to 50:1. ;D

[dnej]

Hey Dan,
Probably old fuel remnants. Could have been in the carbies, or the fuel line.
Also , varnish forms in the tank, and it needs cleaning out.Sometimes, you cant see the coating.
This can also form in the carby, and jets.

Does your motor, (under the cowl) , have a fuel filter built in?
What type of tank is it?
David

[Fishin_Dan]

That's what it's sounding like dnej.... I started off using the old tank (An old metal tank that came with the boat) and the old fuel line... It didn't start till I switched fuel lines, then went dodgy again, then I went to the new tank/new line, and it got going (Although very rough as the damage was already done)... I think I might have to bite the bullet and ditch the old tank/line altogether and get myself another new tank as well... Hmmmm....

Wezza - I have rung around, and everyones booked out till New Year. I unfortunately have to go to Sydney next Friday night, and wont be back till the 2nd Jan, so it's not too bad I guess... Cunningham Marine (Margate) seems to be the cheapest I have found. Anyone know if they are any good?

[Wezza]

Fishin_dan,
Thats a bugger. Did you try wondall road marine in Wynnum??? I might be looking for a deckie on Sunday if you are keen to go out.

[Fishin_Dan]

No not yet mate.... Might give them a call now... :)

Send me a PM with the details, and I may very well be interested!

[Fishin_Dan]

Fishin_dan,
Thats a bugger. Did you try wondall road marine in Wynnum???

Snowed under..... :'(

Oh well... I guess I will just have to wait til after the New Year when I get back from Sydney....

[Wezza]

Okay, I will pm you

[NQCairns]

Wessa all this oil ratio stuff is easy if you know why ;D
The rule is if your engine has allready been run in and it runs needle bearings at the big end then 50:1 is the go. If your engine is low hp enough or old enough to run the white metal shell type bearings then 25 to 1 is the ratio, no other reason comes into it.

Going leaner than 50:1 (50:1 = needle bearings) on oil is reserved for the higher quality oils, like synthetic and a few outboard branded oils. Going richer is reserved for those that want to run the risk of jamming rings etc. nq

[Oldyella]

Wezza
ALL Mercs are 50:1... except oil injected which obviously are mixed by the Autoblender and brand new motors which have a Break in period where higher ratio 25: 1 is advised. Racing Mercs are also higher (25:1)
The little 1. denotes oil injection and suggests that the first tank should be pre-mix and in conjunction with the autoblend would make it 25:1
The little 2 refers to the first tank (new motor) to be 25:1 which is double the oil. If your motor is not oil injected, it's 50:1

[Wezza]

Thanks,
I will keep it at 50:1