4-Cycle oil in 2-cycle outboard

C

canesfan

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Aug 31, 2008
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I mistakenly put 4-cycle 10W-30 Pennzoil "Premium Outboard" marine oil into 12 gallons of gas for a 2 cycle Johnson 90HP outboard engine. Should I cut my losses and drain the gas tank, or will permanent damage result if I ran the engine on this fuel mixture? If I run the current mixture, would it make sense to add the appropriate 2-cycle oil to the tank?
 
ondarvr

ondarvr

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Apr 6, 2005
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Re: 4-Cycle oil in 2-cycle outboard

There was a time when that's all we used, just 30W motor oil. I think if it were me it would now be lawn mower fuel.
 
Silvertip

Silvertip

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Sep 22, 2003
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Re: 4-Cycle oil in 2-cycle outboard

By all means do not use it except in a four cycle engine such as a lawn mower or your tractor. That oil is not designed to be burned. 2-stroke oil is.
 
T

tx1961whaler

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May 31, 2008
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5,197
Re: 4-Cycle oil in 2-cycle outboard

You didn't hurt the motor, but don't run it in there. That is a multi-grade, detergent motor oil that is not good to burn in a two cycle. I used to use straight 30 weight, non-detergent motor oil for many, many years, but newer oils are supposedly much superior to using straight oil, which is not designed to combust.
 
kenmyfam

kenmyfam

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Re: 4-Cycle oil in 2-cycle outboard

Not a good idea. Do not throw it away though, use it in the lawn mower etc as suggested.
 
LubeDude

LubeDude

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Re: 4-Cycle oil in 2-cycle outboard

You "PROBABLY" (Therefore do not do it), could get away with it in a pinch if you do not run the engine hard! I would do like suggested above and run it in your truck or lawnmower!

The oil could separate as regular oil is not designed to stay in suspention like TC-W3 oil is. This would likely be the main issue that I would be leary of!
 
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