Tender 4 Stroke Outboard Oil

ctva

ctva

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Reading through various sites including the Yamaha one, what oil do you use for a small 2.5hp 4 stroke outboard?

Some recommend 10w-40 others 10w-30, some say marine specific, others any good oil of the spec.

Any thoughts?

Thanks.
 
Rock oil MP4 is great stuff. Will do perfectly. Although the manual will tell you yamalube 4 stroke oil. Either will do. It won’t matter between 30 and 40w
 
I just used some 5/30 fully synthetic that I had left over from changing the oil on the car. This was for a Mercury 3.5 four stroke that I owned at the time.
 
ctva said:
Reading through various sites including the Yamaha one, what oil do you use for a small 2.5hp 4 stroke outboard?

Some recommend 10w-40 others 10w-30, some say marine specific, others any good oil of the spec.

Any thoughts?

Thanks.
Click to expand...

Just as you would use a NMMA certified TC-W oil for a 2 stroke outboard you should use a NMMA certified FC-W oil with the SAE viscosity recommended by the engine manufacturer for the ambient conditions likely to be encountered.
 
Is this a small splash-lube engine with no full-flow oil filter?
I which case, some people would suggest a low-detergent oil, of the correct viscosity.
Personally I'd look at what the maker recommended, find something economical which met or exceeded all the requirements, and change it fairly often.

The big deal in a 'marine oil' is a rust test, a steel strip dipped in the oil then exposed to salt spray. A good synthetic oil will probably breeze through this test, but it's up to you whether you want to pay the premium for an oil that's been through the test and got the tick. The results are probably void anyway once your engine's done a few cold starts and got petrol in the oil.

The Yamalube oils are not significantly dearer than what I put in my car.
But then even my car cost more than a 2.5HP outboard.
 
I've just changed the oil on my Suzuki DF2.5, using the manufactures recommended oil, Semi Synthetic Engine Oil 10W-40, NMMA certified FC-W. The W variant has been specially formulated for marine use.

https://www.nmma.org/certification/oil/fc-w

Someone somewhere has gone to the trouble of developing oil to the FC-W spec' and the manufacturer recommends it.

I've no way of knowing whether using the manufactures recommended oil make much difference in the long term, but I figure that the manufacturers don't make any money out of selling oil, but they are interested in the reliability of their engines and their reputation, which is critical to there long term success.

The marginal cost difference of using the recommended oil, when considering the overall cost of boat ownership is insignificant. 0.38L of oil once a year isn't going to break the bank.:)

I also don't relish the prospect of having a long row into a head wind, because the outboard has seized.

I think I'll be sticking to the manufactures recommendation.
 
Spirit (of Glenans) said:
Why has nobody suggested down loading the relevant owner's manual?
Click to expand...
I should say that I have the owner and full service manuals for the Yamaha 2.5.

I’m looking for thoughts on the usual recommendations from the manufacturers on their own oil being the only one suitable.

Thanks for all the comments above and the info.
 
ctva said:
I should say that I have the owner and full service manuals for the Yamaha 2.5.

I’m looking for thoughts on the usual recommendations from the manufacturers on their own oil being the only one suitable.

Thanks for all the comments above and the info.
Click to expand...


Yamaha dont say that!

In the latest owners manuals they say the recommended oil is ..... "Yamalube 4M TC-W or 4 stroke outboard motor oil" ............. They then list suitable SAE and API grades
In older manuals they only say a 4 stroke outboard motor oil and list suitable grades

They do not however suggest that an automotive oil is suitable.
 
Ian_Edwards said:
I've just changed the oil on my Suzuki DF2.5, using the manufactures recommended oil, Semi Synthetic Engine Oil 10W-40, NMMA certified FC-W. The W variant has been specially formulated for marine use.

https://www.nmma.org/certification/oil/fc-w

Someone somewhere has gone to the trouble of developing oil to the FC-W spec' and the manufacturer recommends it.

I've no way of knowing whether using the manufactures recommended oil make much difference in the long term, but I figure that the manufacturers don't make any money out of selling oil, but they are interested in the reliability of their engines and their reputation, which is critical to there long term success.

The marginal cost difference of using the recommended oil, when considering the overall cost of boat ownership is insignificant. 0.38L of oil once a year isn't going to break the bank.:)

I also don't relish the prospect of having a long row into a head wind, because the outboard has seized.

I think I'll be sticking to the manufactures recommendation.
Click to expand...

I don't know that anyone exactly 'develops' oil to these specs, there are plenty of good oils out there, it's a matter of putting it through some tests to get the accreditation. The tests can't be cheap, (seems to involve running in a new 110HP outboard!) so it will bump the price of the oil.
As you say it's only 0.38l of oil, but TBH if it's a relatively new motor that you care about, I'd consider changing it more than once a year. The Yamalube branded stuff is only about a tenner a litre in a big can.
 
Old Harry said:
because others have offered the relevant oil grade info, ( what ever you use in car or lawn mower )
Click to expand...

What I have read above is, for the most part, opinion and anecdote. I would assume that the OP has asked for specific advice regarding the correct viscosity and other relevant specifications and that the obvious place to find such information would be in the owners manual for his particular engine. For my part I would not just put in any old oil I had lying around in my garage or garden shed.
 
It’s always a touchy subject, an oil thread. Lots of opinions...fact is that I’m not aware of an engine ever failing as a result of the wrong grade of oil, within reason. Won’t go wrong with the yamalube recommendation or the rock oil MP4. Must admit I’m a fan of using marine grade oil in marine engines. Why wouldn’t you. It’s not that much dearer and certainly contains additives to suit the Marine environment and infrequent use.
 
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