Why Oil Injection?

[jimmbo]

I don't have many boating memories prior to about 1963, I would have been 3 at the time, but I do remember there was always Outboard Motor Oil, in a Red Plastic Container, from Esso(I think it was Exxon in the US), It said 'Easy Mix' on the Label on the Spine. First time I recall seeing a TCW Oil was in 71, and again it was an Esso Product, called Ultra Marine.

A couple of Television Spots of the Stuff.
View attachment Ultra Marine outboard motor oil. -- [ca. 1971-1972]. -- Imperial Oil television commercial. - ...mp4
View attachment Whitewater rafting on Thompson River. -- ca. 1973-1974. -- Imperial Oil Esso television commer...mp4

 

[airshot]

Yes, I remember those small cans, but I remember (barely) those comming out in mid 60's. I believe it was about 64 when the 50 to one oil mix came about and those smaller cans came out. '59 I had my first outboard, yep, I was 9 yrs old, 3 hp Sea King, with a wrap around rope pull start, think it might have been a 1948. A fellow my Dad worked with gave it to me as it had a horrible knock...my folks could hear me comming down the river from a quarter mile away. We used to get the round quart containers of Standard oil 30 wt, and always had on hand the can opener to open it up. Had a little cup that was just enough oil to mix one gallon of premix. Wasn't until 62 when I had a motor with a 6 gallon tank, a 7.5 hp ScottAtwater with bail a matic, which I needed for my leaky wood rowboat!! Ahhh the memories !!

 

[jimmbo]

OMC didn't market their own TCW Oil until about 66 or 67. Prior to that the manuals stated using Outboard Oil or Non-detergent SAE 30 at 50:1. OMD later put out a Bulletin stating that their Branded Oil could be used in all engines at 50:1. I wasn't scared about using it in our 1957 35hp and our 63 40hp, as they had antifriction bearings throughout the powerhead. Our 64 5 1/2 also got the 50:1, as that was the year OMC officially switched to 50:1, even though the lower Crank bearing was still a friction bearing. I guess OMC figured plenty of Oil would find its way to it, so 50:1 was fine.

 

[racerone]

The 3 bronze bearings in the 5-1/2 and 6 hp are well designed / sized for the job.-----Have had numerous of those engines apart for inspection.----Never an issue with them.

 

[Chris1956]

Gee, a lot of info here. Some of it is even accurate.

Oil injection on modern carb or EFI 2 cycle engines mixes 2 cycle oil with gasoline in the fuel pump and fuel lines, on the way to the carbs or fuel injectors.

Oil injection is more convenient (to some) than pre-mixing. Oil injection also provides an accurate mix of fuel at all times, whereas the gasoline in the pre mix fuel tends to evaporate, giving a richer mixture over time.

Some oil injection is variable ratio, some is constant ratio. It depends on the make model and year of the motor.

Oil injection does not help to clean up emissions. it could lessen smoke somewhat, but does nothing to fix the main emission issue which is unburned gasoline and oil being exhausted during scavenge Direct injection 2 cycle motors use air and some oil only, to scavenge the exhaust, thereby lowering the emissions.

It is pretty simple to accurately mix fuel in a large tank. All you need is a rough guess of how much gasoline you will need to add. You then add gasoline and oil in decreasing increments to get close to a full tank. This minimizes the error of too much or too little oil.

So, let's say you need to add about 50 Gal of gasoline. Put in a 1/2 gal of oil and add 24 Gal gasoline. Now add 1 qt of oil and 12 gal gasoline. Now add a pint of oil and 6 gal gasoline. That makes 44 gal of mixed fuel. Now add 8 oz oil and 3 gal of gasoline. If you still have room in the tank, repeat the 8oz oil/3 Gal gasoline, until she is full. If you screw up, it is only a few oz of oil across 50 Gal of gasoline. This works for any amount of fuel and will get you real close to the exact ratio you want.

 

[racerone]

On an E-tec the oil is NOT mixed with the gasoline.-----And I believe other direct injection 2 stokes do NOT mix oil with the gasoline.

 

[Scott Danforth]

direct injection is fuel directly injected into the combustion chamber

 

[racerone]

Fuel injected into the combustion chamber does not need oil !!

 

[Captain Caveman]

So emissions, convenience, and less oil fouling seem to be the motivations. I seem to have run into more than a few people who, frustrated by finicky alarms and a desire for simple foolproof ( provided you can read side of a 2 stroke mix bottle) systems, remove/bypass the oil I injection equipment.

If I remember correctly, I think that there are a few brands / model years that are notorious for having oil injection issues. On those motors, some folks have gone back to pre-mixing. I don't remember the brands so I won't guess.

I still use a 1957 Johnson 3hp and a 1963 Johnson Seahorse 5.5hp motor. When I fill those I dump in a little gas, add the oil, and then blast it with gas from the pump. Then I drive down the road 15min to the lake. By the time I get there, the oil has mixed in pretty well with the gas.

 

[jimmbo]

A full tank cannot slosh much, and sloshing doesn't really do much mixing. The gas at the top moves a bit, but the Oil at the bottom just slides back and forth a bit. Some people think that tipping the tank over once or twice mixes the contents. In reality the Tank rotates around the contents, and if the oil is at the bottom of the tank prior to rotating, it is pretty much still at the bottom after. Stirring is likely the best way to insure a good Mixing, Shaking is Good, as is repeated rapid Inverting, but only on half filled tanks.

 

[JimS123]

I have motors in my collection going back to 1919. Back then you added oil to the tank.

I have had oil injected motors as well. I can't say that any of them worked reliably year after year. Always something that needed repair in the system.

I have never had an oil added motor that gave me oil related "problems". Oh sure, they smoke a bit and I'm sure I'm hurting the environment because at time it uses more oil than necessary. But, I don't have any hassle.

I found the perfect solution. I still run some old smokers once in awhile just for boat shows and just for fun. But all my daily drivers are 4-strokes. OK, yeah they cost more. One of the 11 rules in retirement is hassle elimination. I follow that to the T.

 

[airshot]

I rememver my younger days, 50-60's mixing oil and gas. The small local marine mechanic was a friend, his instructions were to add 1/3 tank of fuel and pour in the oil, shake and mix vigorously..add anither third of gas, mix some more, the add last third. Still use that method to this day. Now I have an oil injection Merc, awesome, just fill the oil tank every couple weeks and top off the gas tank. Had two OMC vro units that had issues, even the dealer recomended switching to premix. This 1992 motor has had NO issues since new other than the low oil warning washer issue, but I just dont bother with fixing that. Just top off the oil tank with each fuel fill..

 

[jimmbo]

I like the old Smokers, they keep Mosquitos at bay.