I’ve spent almost two hours researching this. There are plenty of places that will sell you special “outboard oil” but I’ve heard you may substitute auto oil in its place. No one will officially say that though because they want to sell you more oil and not get sued.
We have an outboard Mercury 125 HP 4-cycle oil injection engine. We do not mix the oil with the gas, but put it in an oil intake that has a dip stick.
We don’t have the exact oil the marketing says to use, but we do have some 2-cycle lying around (that we use on another boat where we do mix it in with the gas) and some 10W-30 for the car.
Which would be worse to use in the 4-cycle outboard? The cycle-2 oil, or the auto oil? Or both?
Thanks
Auto Oil October 31st 2009
October 9th, 2009 at 7:56 pm
You can’t have “OIL INJECTION” on a four stroke engine, it has oil in the crankcase that needs to be changed like an automobile changes it’s oil. “VRO” or “Oil Injection”, is for a 2-stroke engine, you CANNOT use 10-30 motor oil. You MUST use 2-stroke outboard oil that is “NMMA” National Marine Manufacturers Assoc.) certified, or “B.I.A” (Boating Instatute of America) certified. Your oil should be “TC-W3″ rated (Two-Cycle Water cooled), the “3″ means that “Teflon” was added. The 2-stroke oil is “ASHLESS” and “LOW SMOKING”, and specifically made for outboard engines. The “Detergent” quality’s in regular 10-30 motor oil will cause sticky rings, “Sticky Rings”, will turn an outboard 2-stroke engine into a piece of “TOAST”, I highly recommend that you “NOT” add motor oil, only properly rated 2-stroke oil recommended by the manufacturer.
October 9th, 2009 at 8:25 pm
Both are bad.
4 cycle oil is not designed to be burned. It forms carbon when burned that will stick the rings in the pistons on 2 cycles. This oil will also wash off the cylinders with gas. Engine wear and damage will result.
2 cycle oil that is designed to be mixed with gas may be much thicker and not inject correctly with oil injection.
Get the correct oil or you may cause serious damage in short order.
October 9th, 2009 at 8:48 pm
sorry, but you don’t have a 4 cycle oil injected engine. any name brand 10w30 or 40 will suffice. don’t use 2 cycle oil.
October 9th, 2009 at 9:06 pm
4-cycle outboard engines are uncommon, and have only gained popularity in the past few years. Perhaps it is a 4-cylinder, 2-stroke engine. The fact that you say it has an oil injection system tells me that this is just a fancy way to mix the oil with the gas so you don’t have to do it. Plus, it is a more environmentally sound system than standard 2-stroke outboards.
You will need to use the special marine 2-stroke oil. It should be readily available at your local auto parts store. Using standard auto oil will burn/smell awful, and may damage the engine over time.
October 9th, 2009 at 9:18 pm
i would use the motor oil not the 2 cycle.i use motor oil in my 60 horse Johnson and have never had a problem.you might want to call a marina and tell them your prob bob. good luck
October 9th, 2009 at 10:07 pm
I would suggest that you do more research on your engine.
Typically 4strokes don’t have oil injection. The bottom ring on the piston is called the oil ring, its job is to keep the oil out of the combustion chamber. This is why you typically don’t need to add oil to your car every time you add fuel.
2 strokes typically get their lubrication from the oil in the fuel.
If you have a oil tank separate from the engine, typically you have a 2 stroke.
Why i keep putting typically in there, is there are some exceptions to the rules, (I have a 2stroke that has valves and does not take oil in the fuel).
Main difference in auto oil and marine oil is the additives they put in for handling water. Humidity and chance of getting water in the oil is higher in a boat. I have used auto oil in inboards with no problems.
marine 2 stroke oil and weed eater oil differs that the temperature ratings are different. You can use weed eater oil in a outboard (water cooled) but you will fry a air cooled weed eater with marine oil.
April 22nd, 2010 at 4:16 pm
I agree with the people above. Dont use the 2 cycle oil, it will cause you more problems. Get teh right grade for the engine and youll be motoring, literally.
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