Motor oil 5W-30 okay even though 10W-30 recommended?

[senkosam]

I have a 2.5 Mercury and have been using 5W by mistake. Any problem? Just ordered 10W just in case.

But one thing I didn't realize was the oil level indicator window's accuracy depends on the motor being perfectly level or it may indicate an over- or under fill. Been there/did that until I bought a level.

 

[airshot]

The only real difference would be extreme high heat, where 10w would hold viscosity better then 5w. Make the proper change, you should be fine....
Checking oil in 4 stroke engines on a boat has always been a challenge. When I had my I/O it was no different. I drained my engine, replaced the filter and filled with merc recommended amount of oil. With my boat sitting in its storage position on the trailer in my barn, I made the mark on the dip stick. Now I had proper amount of oil and used the mark on my dipstick as the new full mark and only check when the boat is in storage position.
On your little motor, I would drain, then add recomended amount of oil, the find a position the motor will be stored in so you can repeat that position each time you check the oil.

 

[lckstckn2smknbrls]

Any oil is better than no oil.

 

[bigcity]

The only real difference would be extreme high heat, where 10w would hold viscosity better then 5w.......

5w/30 vs 10/w30 are both considered a 30 weight oil when measured at normal operating temps(100°c/212°f), and will remain the same viscosity at any temps at/near/above that.
The 5w/10w is the oil's viscosity when measured at low temps(0°c/32°f). And really only tells you how the oil flows when really, really cold, at startup.
So, unless you are using that outboard in really cold weather there is ZERO issue with using either oil. Even then it will only be at startup. But, BUT, that is where the vast majority of engine wear happens.
Jeff

 

[airshot]

5w/30 vs 10/w30 are both considered a 30 weight oil when measured at normal operating temps(100°c/212°f), and will remain the same viscosity at any temps at/near/above that.
The 5w/10w is the oil's viscosity when measured at low temps(0°c/32°f). And really only tells you how the oil flows when really, really cold, at startup.
So, unless you are using that outboard in really cold weather there is ZERO issue with using either oil. Even then it will only be at startup. But, BUT, that is where the vast majority of engine wear happens.
Jeff

Yep, I got that backwards, shoukd have been cold not hot, thanks for the correction.

 

[Wayne Roberts]

No worries.............Not gonna hurt a thing.......................

 

[senkosam]

Whooo, thanks for the info!
It put my mind at ease though I still got a $33 jug of 10W30 coming I don't need.