Oil for Yamaha F300 outboard

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Been running Yamalube 4M FC-W 10w-30 on these four strokes. Going to switch to synthetic, for many reasons including use is offshore. Was thinking Yamalube 4M FC-W 5W-30 synthetic. Any thoughts on whether there is a better and/or cheaper synthetic option?

Alos, what is the difference between the FC-W and FC-W (CAT) certifications? Do they overlap?
 
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I just read this on Yamaha's site:

How often will I have to change my oil? Do I have to use "special" oil for the 4.2 liter V6 Offshore outboards?
No "special" oil is required, but whatever oil you choose should at least be certified with the National Marine Manufacturer's Association (NMMA®) FC-W® stamp of approval for marine use. Yamalube® 4M in 5W-30 weight (fully synthetic), or 10W-30 or 20W-40 weights (mineral), has such approval and is manufacturer-recommended. Using Yamalube 4M is important because it has the chemical formulation and corrosion resistance necessary for marine engines. Automotive engine oils do not measure up to this standard. If Yamalube 4M is not available at your local Yamaha Marine dealer, your next alternative is to use good-quality motor oil, rated API SE or higher, in either 5W-30 or 10w-30, or 20W-40 until Yamalube 4M can be obtained. In either case, we do not recommend exceeding 20W-40-weight engine oil in our 4.2L V6 Offshore outboards.
 
Mystik JT-4 10w30 synthetic FC-W Amsoil would also be a great choice and is dual rated for CAT rating biggest factor has to deal with Ash content.
 
I have a smaller Yam4s - switched to Royal Purple HPM (M is marine) it carries all those certs ... CC and all ...
 
Now why would a sealed system internal engine crankcase need corrosion protection? Almost any oil is, by its nature, an anti-corrosion substance ... Yamaha does sell nice oils and I used to run their stuff in various engines. But it is not all that easy to get.

If we are talking about upper cylinder corrosion due to one valve being open to wet exhaust on shut-down, and condensing marine air moisture as it cools, the best protection for that is SAE30 straight grade w/o VII's.

Most modern oils exceed SE, so that's not an issue. NMMA cert does not mean stringent additional testing and I'll bet it's not required outside the USA ...

So what to do if not using YamaLube? I'd go down to the local Napa Auto Parts store and buy their full synthetic 5W-30 or 10W-30 (either will do fine as they are both 30 at op temp) for $2.99 a quart while on sale and run that until the netherworld freezes over
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The big deal is to make sure you idle the engine down to let it reach uniform temp as you shut it off. And then to raise the lower unit and and lay it over on the preferred side. If you are really concerned, you can trash bag the lower unit to stop air transfer so that it cools without additional sea air backing into the open cylinder. But there is enough salt water inside the lower leg that will happen anyway unless you completely flush with fresh water every time.

And how many outboard have anyone seen that seize up from corrosion sitting dockside in less that say 6 months of non-use ... It just does not happen. Outboards are tough and they do not have these sorts of issues. The best thing is to run it often
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All the commercial operators I have seen use HDEO 15w-40 in all their gas powered marine engines .Inboards and out boards.
 
The standards are based on labs tests - similar to ILSAC - more about emissions and fuel economy and still protect the engine.
Endless chase by our Big Brother ... Who'd have thunk we'd have to worry about cat friendly boat oils ?
But you know where the OPE regs are cranking up - like when there was a 49 state mower at Sears !
(Glad my small boat only holds 2 qts)
 
Just one F300 motor is the price of a new mid sized car. You run what they say under warranty ... And use good judgement after that. My buddy has 3 X F350 ... Don't even try to get him off the 4M Yammy gold bottle ...
 
Yeah, they are big $$ for sure. Under warranty - you bet, use their oil and document it.

After warranty, it's your call. By then, if the engine was going to break, it would have
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Good points on the warranty. I'm almost 3 years into a 5 year warranty, with about 700 hours on them. Guess I'll stick with Yamalube synthetic 5w-30 (gold bottle) till out of warranty. Just pains me to pay that much for oil, when I know it's probably essentially the same thing as oil half the price, and a pita to get my hands on.
 
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Each person interprets what they read in an owners manual however they want to. Like many threads on BITOG - some go right to truck oil - where some stick with what the OEM recommends as it relates to specs - you don't have to buy their brand (not just one OEM or oil provider in this case).
FC-W is indeed a pay to play system - they test for a dozen parameters - some you would recognize - some specific to these high tech outboard motors.
Those that stick with spec oil - start to shop for the best deal - sometimes via Amazon or wherever.
To each his own.
 
These are the recommendations from the F300 manual


SAE 10w-30,10w-40,5w-30
API SE,SF,SG,SH,SJ,SL

SAE 15w-40,20w-40,20w-50
API SH,SJ,SL
 
Originally Posted By: Stewart Fan
I run Rotella 10w-30 in my F300

There are a ton of oils that'll meet the owners manual requirements.





Last night I forgot to mention I'll be using 10w-30 Castrol Edge with titanium for the next few changes. I picked up 30 qts during Auto Zone's $2 clearance last winter.
 
Originally Posted By: RTexasF
I just read this on Yamaha's site:

How often will I have to change my oil? Do I have to use "special" oil for the 4.2 liter V6 Offshore outboards?
No "special" oil is required, but whatever oil you choose should at least be certified with the National Marine Manufacturer's Association (NMMA®) FC-W® stamp of approval for marine use. Yamalube® 4M in 5W-30 weight (fully synthetic), or 10W-30 or 20W-40 weights (mineral), has such approval and is manufacturer-recommended. Using Yamalube 4M is important because it has the chemical formulation and corrosion resistance necessary for marine engines. Automotive engine oils do not measure up to this standard. If Yamalube 4M is not available at your local Yamaha Marine dealer, your next alternative is to use good-quality motor oil, rated API SE or higher, in either 5W-30 or 10w-30, or 20W-40 until Yamalube 4M can be obtained. In either case, we do not recommend exceeding 20W-40-weight engine oil in our 4.2L V6 Offshore outboards.



My manual says this. Must be FC-W certified.
 
RP HPM is $7.68/qt on eBay for synthetic FC-W stamped - and free shipping starts at $95.
It comes via Jegs the performance company - available in 10w-30 & 10w-40 - RP always touts film strength - but I could not find the HTHS ... Anyone know ?
 
Originally Posted By: claluja
Originally Posted By: RTexasF
I just read this on Yamaha's site:

How often will I have to change my oil? Do I have to use "special" oil for the 4.2 liter V6 Offshore outboards?
No "special" oil is required, but whatever oil you choose should at least be certified with the National Marine Manufacturer's Association (NMMA®) FC-W® stamp of approval for marine use. Yamalube® 4M in 5W-30 weight (fully synthetic), or 10W-30 or 20W-40 weights (mineral), has such approval and is manufacturer-recommended. Using Yamalube 4M is important because it has the chemical formulation and corrosion resistance necessary for marine engines. Automotive engine oils do not measure up to this standard. If Yamalube 4M is not available at your local Yamaha Marine dealer, your next alternative is to use good-quality motor oil, rated API SE or higher, in either 5W-30 or 10w-30, or 20W-40 until Yamalube 4M can be obtained. In either case, we do not recommend exceeding 20W-40-weight engine oil in our 4.2L V6 Offshore outboards.



My manual says this. Must be FC-W certified.


The way I'm reading this, it is not required but suggested. I highly doubt they could deny warranty because the oil was not NMMA approved.
 
I've been using NAPA 15-40 Universal Fleet diesel rated oil in my Yamaha F115 for 6 years, and never a problem. Send it to glackstone and all is good they report. This engine spends most of it's life at 5000rpm. Diesel oil is the same as FWC rated oil just compare the MSDS. It is also $2.50 a qt.
 
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