Tohatsu engine oil

billstoy

Recruit
Joined
Mar 22, 2010
Messages
3
Looking for alternatives to the Tohatsu brand oil for my 2016 15hp 4-stroke motor. The manual states "Use NMMA FC-W certified 4-stroke engine oil below. 10W-30: is recommended for use in all temperature.25W-40: may be used at temperatures above 4°C (40°F)".
Since I operate it in some icy waters in the spring I want 10W-30, however all the local stores only carry synthetic oils. I've seen older posts saying not to use synthetic in the Tohatsu, but not sure why. Can anyone offer insight on this? Is a synthetic like Lucas (NAPA) 10W30 OK?

Thanks
 

tpenfield

Moderator
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Jul 18, 2011
Messages
17,620
For the most part . . . oil is oil. Brands tend to be labels and not unique specifications.

If you Google "NMMA FC-W certified 4-stroke engine oil" you will find some resources and lists for alternate brands that meet the NMMA spec.
 

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
The Owner's Manual states : API, SH, SJ or SL 10W-30, Approx. 1000 (33.8) Don't know if any is a synthetic one...

Happy Boating
 

pvanv

Admiral
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Apr 20, 2008
Messages
6,500
All 4-strokes make oil. Heavier oil and synthetic oils increase that. NAPA 10w-30 is OK.
 

billstoy

Recruit
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Mar 22, 2010
Messages
3
Thanks for the replies.
So it sounds like synthetics are fine as long as its FC-W, and from what I read its preferred for trolling motors running in cold water.
Paul, what do you mean by 4-strokes make oil?


Bill
 

pvanv

Admiral
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Apr 20, 2008
Messages
6,500
4 stroke crankcases run cold, and don't boil off the blowby gasses. That ends up increasing the oil. That's the case for all 4 strokes of all brands.
 

MattFL

Master Chief Petty Officer
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Oct 20, 2010
Messages
827
Thought I responded, but it didn't post? Anyway, as long as the label on the oil meets or exceeds the requirements in the manual, there's no reason not to use synthetic. Actually I would think it's preferred. As for making oil; I hear it happens more up north for motors that don't get up to full temp very often or for very long, but down here in FL it only happens if you idle around a LOT or if something is wrong with the motor. In the more than 20 years I've been running 4-stroke outboards, my oil level has never increased between changes. Water temps here are typically mid 80's F in the summer, mid 70's F in the winter, and air temps are 80's-90's F in the summer, 70's-80's in the winter.

Oil wise; I've got a little 6HP Tohatsu and with the 10-40 conventional oil it will smoke briefly and you can smell the oil burning after long full throttle runs, but switching to the fully synthetic 10-50 oil that I run in my motorcycles resolved that 100%. I don't know that synthetic vs. conventional had as much to do with it as the synthetic is just a much better oil in this case.
 
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