gas /oil ratio

billyboy72

Cadet
Joined
Nov 12, 2008
Messages
17
have 1987 mercury 2 cycle 75 hp motor. I mix the oil/gas mixture at 50-1 ratio. seems the engine is quite old, it seems a bit smokey, but runs good. What is the least amount of oil that is ok to mix with the gas and still have the engine lubricated safely? THANKS
 

Beefer

Lieutenant Commander
Joined
Aug 4, 2008
Messages
1,737
Re: gas /oil ratio

iagree.gif
 
D

DJ

Guest
Re: gas /oil ratio

50:1. I it smokes, you have other issues.

1. Severe carbon build up. See (Decarb. thread-in FAQ's)

2. fresh fuel/oil mix.
 

5150abf

Vice Admiral
Joined
Aug 12, 2007
Messages
5,808
Re: gas /oil ratio

Do a decarb, that should help but what you need to understand is no smoke no lubrication.

The only oil in the engine is what is in the gas(exept for lower unit) so you don't want to skimp on it, less oil less lub= faster wear.

I go 3 oz per gallon and then add a smidge, rather use a little more oil and know the engine is protected.
 

billyboy72

Cadet
Joined
Nov 12, 2008
Messages
17
Re: gas /oil ratio

Thanks everyone for the info. will do as you suggest. thanks again.
Billyboy72
 

pvanv

Admiral
Joined
Apr 20, 2008
Messages
6,570
Re: gas /oil ratio

Of course, you can run Amsoil Saber OB oil at 100:1 in a 50:1 application. I have done that in my old Evinrude 15 for years. Half pint per 6 gals. of fuel instead of 1 pint in 6 gals. Less oil=less smoke. But it has to be the GOOD oil.
 

pecheux

Lieutenant Junior Grade
Joined
Jun 9, 2006
Messages
1,200
Re: gas /oil ratio

Of course, you can run Amsoil Saber OB oil at 100:1 in a 50:1 application. I have done that in my old Evinrude 15 for years. Half pint per 6 gals. of fuel instead of 1 pint in 6 gals. Less oil=less smoke. But it has to be the GOOD oil.

Been there, done that with my 1997 Force 15 hp. Best idling ever, very little smoke, ... BUT the exhaust was a TROAT IRRITATING STINKER which is the reason I stopped using it. (My boat is tiller controled)
 

Frank Acampora

Supreme Mariner
Joined
Jan 19, 2007
Messages
12,004
Re: gas /oil ratio

OR: as I was reading somewhere: Evinrude engineers did some testing and came up with the result that you could run the engine all day with no oil in the gas as long as you kept RPM under 2500. Retained oil in the crankcase was sufficient at that load.

Would I do it? Only on an engine I didn't care about rebuilding. I trust the engineers, I don't trust Murphy. There was also the Mobil 1 advertising where they drained the crankcase of a Chevy and drove it around Manhattan N.Y. with no damage. I wouldn't do that with my daily driver either.

Point is: VRO engines vary oil from 100-1 at idle to 50-1 at full throttle. If you don't intend to power at full throttle for long periods, you could probably "get away" with 75-1. Mind you, this is a guess. I have never tried it.

I also seem to remember reading somewhere that the big engine makers never approved of "100-1 oils"
 

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,226
Re: gas /oil ratio

OMC did say 100:1 in their motors for a very short while, aroundabouts 1985. But they quickly retracted the advice and went back to 50:1. Where I used to work, they called that a FEEBE. (Unprintable).
 
D

DJ

Guest
Re: gas /oil ratio

OMC recanted their 100:1 recoomendation not because the engines couldn't handle it. They recanted because 100:1 did/does not leave enough residual oil to protect internal shiny parts from corrosion.
 

pecheux

Lieutenant Junior Grade
Joined
Jun 9, 2006
Messages
1,200
Re: gas /oil ratio

OMC recanted their 100:1 recoomendation not because the engines couldn't handle it. They recanted because 100:1 did/does not leave enough residual oil to protect internal shiny parts from corrosion.

Back then, I wonder if OMC had a special 2 cycle oil that was made exclusively to match their 100:1 mix recommendation or were they sugesting to use their normal 50:1 oil at a 100:1 ratio ? Amsoil Saber DO write & claim that their oil was MADE to be used at 100:1 ratio ...
donno ???
 

coolguy147

Commander
Joined
Jul 14, 2008
Messages
2,817
Re: gas /oil ratio

all i know is never run my motor past 24:1 mix lol dont wanna take a chance with my little ten
 
Top