Gas - Oil Mixture on old Evinrudes outboards

[Bellasdad]

Hi I have 3 older Evinrude outboards a 1967 3hp, 1960 10hp and a 1955 7.5hp. My question is this, what is the best gas/oil mixture for these motors ? I have read that 24:1 is the most preferred mixture . With the modern oils out there should I change from that ? I am going to be using the Evinrude 2 cycle oil.Can that mixture be used in all 3 of these motors safely ? Thanks Joe

 

[Scott Danforth]

The 67 may be 50:1, the other two are 24:1

 

[cyclops222]

I have been doing 50 to 1 in the 1986 30 hp. And 100 to 1 in the 1999 ......9.9 for at least 20 years. No problems.
The oil quality is so good now.

 

[Chris1956]

OMC motors before 1964 often had sleeve bearings, versus roller bearings. Sleeve bearings need more lubrication, hence the 24::1 recommendation for all OMC motors before 1964.

As for the 100::1 gas/oil mix, the drawback was loss of crankcase rust control, with so little oil in the fuel. I believe OMC changed the 100::1 recommendation back to a 50::1 fuel mix, for all 2 cycle motors.

 

[Crosbyman]

oil is cheap... motor are expensive.... go 24/1 on oldies 50/1 on non-oldies

 

[Nordin]

As Chris1956 says, engines with bronze bearings in the connecting rods to the crank shaft need 24:1 mixture, engines with roller bearings go for 50:1.
I think but might be wrong, when OMC used dual line fuel hose for the fuel tank (pressurised tank) the mixture has to be 24:1.
I think they change over to single line hose in 1962-63 or maybe 1964.

 

[jimmbo]

OMC started using the Single Fuel Hose as Standard Equip on the High End Motors(some 35s and the V4s in 1958), though it had been offered in the Accessory Book for a few years, so the engines could be used on Boats with Large Fuel Tanks.
From 1957, on, the Big Twins and V4s all had Antifriction Bearings and could safely run the 50:1 Mix. In 64 OMC speced 50:1, even on the Engines that still had Friction Bearings, and this was before TCW Oils were around.

 

[saltchuckmatt]

If your just idling around just use very little oil (100 to 1)

If you want to rip around use 16 to 1....

Otherwise use 0 to 1 and put them on the wall. Years of staring at them will do you wonders.

 

[jimmbo]

If the Bearings are Well Lubed at the Specified Gas-Oil Ratio, more Oil doesn't make them Run Smoother. 16:1 was used prior to the Mid 50s. Some Engines, like the British Seagull, used a 12:1 or a 10:1, even in the 70s. They were Great for keep Mosquitos at bey

Most engines from the 70s can idle on 100:1, and for a While in the Mid 80s OMC did spec it, they did recall that, and said to use 50:1
100:1 was used in the Early-Mid 60s by Mcculloch Outboards, but required a specific Lubricant they marketed

 

[saltchuckmatt]

Yes, I can make just about any 2 stroke outboard run excellent on 100 to 1. And I have a 63 brass British Seagull that runs on 16 to 1.

I just really thought, starting them once and then hang them on the wall and maintain them is WAY more fun the running them around at high speeds.

I believe they'd lived a good life and deserve to be put out to stud!

SaltChuckMatt

 

[ct1762@gmail.com]

Yes, I can make just about any 2 stroke outboard run excellent on 100 to 1. And I have a 63 brass British Seagull that runs on 16 to 1.

I just really thought, starting them once and then hang them on the wall and maintain them is WAY more fun the running them around at high speeds.

I believe they'd lived a good life and deserve to be put out to stud!

SaltChuckMatt

its weird the 4hp motors with bronze bearings all 'round... ive had 3 in a row at my shop a few years ago all with shot/scored/melted bearings from lack of lube. all 3 were 1971/72 models and nearly identical damage. owners swear they used good tcw3 but at 50:1. still scratching my head on those!

 

[Crosbyman]

if you dont shake the can the oil doesn't not mix and you run on near 0/1 for a while . Millions of those 4hp still run good so the problem wasn't the bearings....

 

[silverbul]

just a share.

 

[airshot]

Big difference in using a 50 to one oil ratio and properly mixing oil at a 50 to one ratio !! Often folks do not mix properly !! Worked at a Marina in my younger days, scary how some folks mix their fuel, no wonder there are engine issues !!

 

[jimmbo]

Yes, I have watched People meticulously measure the Proper amount of oil, fill the tank, pour the Oil in, put the Cap on, start the Motor and go... Contrary to what the Oil Makers say about easy mixing, it isn't self mixing.

 

[Bellasdad]

Thank You all that replied. I am going to play it safe and run all 3 at 24:1.

 

[flyingscott]

OMC motors before 1964 often had sleeve bearings, versus roller bearings. Sleeve bearings need more lubrication, hence the 24::1 recommendation for all OMC motors before 1964.

As for the 100::1 gas/oil mix, the drawback was loss of crankcase rust control, with so little oil in the fuel. I believe OMC changed the 100::1 recommendation back to a 50::1 fuel mix, for all 2 cycle motors.

Everybody thinks there was this great engineering change at OMC in 1964. there was not. Powerheads from the late 50s were the same as the later ones. They were still using bushings in later motors. What changed was the oil recommendation nothing else.

 

[racerone]

Board room decision to promote 50:1 as the general public thinks "----if it can run at 50:1 mix it must be an improved motor "-----I say it all the time oil mixed with gasoline and 2 stroke lubrication is NOT well understood.

 

[cyclops222]

YAWN

 

[cyclops222]

There is only 1 way for a D I Y person to ...Completely ...mix the 2 liquids together.
And KNOW they are protecting the engine from friction wear.