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Thread: Motor oil in a 4 stroke

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    Default Motor oil in a 4 stroke

    What do you use - auto or marine grade oil? Argument is marine grade is better for you outboard since you are running engine at higher RPMs.

    what u think?

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    Moderator stid2677's Avatar
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    Quote Originally Posted by akroxy View Post
    What do you use - auto or marine grade oil? Argument is marine grade is better for you outboard since you are running engine at higher RPMs.

    what u think?
    Marine grade oil has more corrosion preventatives.
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    Chevron DELO 400 15w-40 .

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    Member Dan in Alaska's Avatar
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    When I bought my 22-ft Hewescraft (brand-new from Deweys) back in 2003, they said to just run regular 10W-30 automotive oil in my new F115. They said changing the oil regularly was more important than brand, as long as the oil met the proper API rating (SM, SL, SJ, etc.) spelled out in the owner's manual.

    I sold that boat a few years ago. A friend now owns it with over 900 hours on the engine. There has NEVER been an oil related issue with that engine. In my subsequent boats, I've always run regular automotive oil and never had an issue with them, either.

  5. #5

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    I'm on the Kenai River and run a 50hp Yamaha 4 stroke. I've got over 2500 hours on it and I've been running automotive 5W30. Have not had a single problem to date.

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    I use Yamaha's marine 4-stroke oil. I looked up the oil specs and it was different enough to persuade me to not use my car-grade Amsoil. For once a year oil changes I'm not worried about the few cents more for Yamaha oil. I use Amsoil in my 4-stroke snowgo, though, so no I'm not a Yamalube fanatic.

    Didn't Amsoil come out with a marine 4-stroke oil? If it meets the specs, I'll use that.

    EDIT: Bingo, Amsoil does offer a marine motor oil. That's what I'll use come springtime. http://www.amsoil.com/StoreFront/wct.aspx

  7. #7

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    Changed the oil today, used NAPA premium motor oil with all the appriopriate seals of approval. Interesting that my Yamaha outboard handbook does not say anything about "marine grade" oil. Just that you should use 10-30 or 10-40 with the appripriate seals of approval.

    What U think

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    From my Yamaha manual...

    Recommended engine oil:
    YAMALUBE 4-M FC-W oil or 4-stroke motor oil with a combination of the fol- lowing SAE and API oil classifications
    Engine oil type SAE: 10W-30 or 10W-40 Engine oil grade API:
    SE, SF, SG, SH, SJ, SL
    http://www.yamahaoutboards.com/owner...owners-manuals

  9. #9

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    Maybe I need to do a little more research BUT aren't our gasoline cars and trucks 4-stroke motors?

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    Yes your car is a 4-stroke... but the engine isn't standing on it's end with saltwater at 40degrees flowing all around it. The FC-W rating is what is important about the "seals of approval/ appropriate ratings." it stands for FourCycle-Watercooled and is designed for the amount and type of shear forces in Outboards and has additive packages to handle the eventual saltwater presence in your engine from either condensation or intrusion.
    Amsoil makes a good product, so do the outboard manufacturers. Whatever you use, be convinced it is a quality oil, "the best because it's the cheapest."
    Casey
    Yamaha Dealer
    Petersburg, AK

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    Saltwater won't get in via condensation. Salt cannot accompany water vapor anywhere.

    A while back, an esteemed (paid) contributor to the guns/reloading part of this site tried to sell the notion that salt could cross a still room via vapor transport. When challenged, posts disappeared, the fellow challenging him was banned, and he changed his occupation from "ballistics engineer" (which carries with it some implication of accredited schooling/training in physical sciences, such as phase changes, transport phenomena, etc.) to "ballistics expert" or some such and is still posting as an "expert". Life's not all milk and cookies around this site.

    Back to the topic at hand. In a mist or spray situation, salt carried by spray or remaining airborne as dust after the droplet it was in evaporated can make its way into your crankcase in a couple of ways: past the rings if drawn in with the combustion air charge, or through crankcase ventilation. You gotta be running in an awful lot of foul weather for this to happen. What does this salt do? Salt is partly soluable in oil, so some will dissolve. Remaining salt will either float along with the oil if really small or plate out on the oil filter element if the particle is large. Wherever it is exposed to humid air, it can pull moisture from it. Whenever the oil is brought back to operating temperature, however, any water in the crankcase will boil off. Great case to run your boat often, and change oil after your peak season is thru versus before the next.

    As for outboard cooling, it's no different than a gas pickup truck pulling a load uphill on a really cold day with no radiator cover. Coolant returned to the engine in that case will be quite cold, possibly well below 32F as it's a glycol mix and not subject to freezing until below ambient temperature. Thermostats on an outboard regulate temperature of the water leaving the engine block, just like in a car. If anything, an outboard has a more favorable cooling situation than a car, due to the much narrower range of anticipated cooling water supply.

    I'd also like an explanation of how oil in an outboard gets worked more than oil in a car. Take the BF225 honda on the back of my boat. It's a 3.5L 24V v-6, same as is found in similar year honda minivans and SUVs. As long as the oil will keep a hydrodynamic wedge at the rod/main bearings, lubricate cylinder walls, lubricate valvetrain, and cool parts not directly cooled by the water jacket, I'm pretty happy. The only place you could argue that outboard oil gets worked harder than auto oil is on the main and rod bearings, and again, I'd need to see some sort of analysis comparing pricy OEM oil versus costco chevron before being convinced that "marine" 4-stroke oil is needed.

    I use Mobil 1 bought on sale at Costco for a bit more than $4/qt. I'd run delo or chevron 10/30 as well, and have.

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    Short answer, the manufacturer recommends certain specs and requires them for warranty compliance. I'm too lazy to remember all the S designation requirements but I seem to recall FC-W just fine. As for differences between outboards and autos? My outboard runs consistently at RPMs twice or more than my car and truck engines. My outboards also spend considerably less time in low power/idle situations, like at stoplights and in traffic. My car doesn't park for months on end with the engine within 12-15" from a water source, and that's through all the temperature swings that day and night have to offer, let alone the temp swings from engine operation. Honestly, I've wondered about using airplane oil in my outboard since operationally my boat is more typical of an airplane engine than of a car, but again, considering the clear recommendations from the manufacturer I'm not motivated to try. I assume any oil will work better than no oil. Since we're splitting hairs I also assume Marine-spec oil must have advantages over other oils that don't meet those specs.

    All that said, I don't give a rip what other guys use. I'm only reporting my own attitudes.

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    Saltwater won't get in via condensation. Salt cannot accompany water vapor anywhere.
    Good point. I appologize for any confusion. I think Mr. Pid adequately summed up how your outboard's conditions are different than your minivan's.

    I hope the OP got enough good info from this thread to make an informed decision.
    Casey
    Yamaha Dealer
    Petersburg, AK

  14. #14

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    Thanks for all the great input and discussion. Everyone has an opionion... educated or not and the key is "making that informed decision"

    So how does synthectic oil match up?

  15. #15

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    This discussion is something else. I am not a lubrication expert, but a good quality oil isn't going to give you trouble in a marine application. It goes without even saying millions of boats have logged countless hours on automotive grade dino oil. The most likely thing that is going to happen is your motor will corrode away from the outside before you would have to worry about lubrication failures on the inside. I have a pair of hondas that haven't been babied that have great compression, very good oil pressure, and are still as powerful as they were decades ago and I put whatever Chevron weight oil I picked up at costco for the cars and trucks. Of all the things to worry about, this is pretty insignificant I would say.....

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    When I think of "wearing out" or physically changing a viscous fluid, I think of cycles. Heating/cooling cycles, pressure cycles, etc.

    If an outboard on average spends its 100-hour run time between oil changes revving twice as fast (on average) as a minivan engine with a 3000 mile oil change interval with average speed of 30mph (equals 100 hour runtime), then the outboard's positive displacement gear pump that pumps engine oil moves twice as much oil through a pressure cycle. But he BF225 crankcase at ~8qt holds nearly twice the oil that the odyssey minivan holds (4.5qt), so each molecule of oil sees roughly the same number of pressure cycles (trips from crankcase pressure to oil pump discharge pressure and back) in both engines over both oil change intervals.

    If the minivan racks up its 3000 miles in 10-mile chunks with full cooldown between runs (commuting), that's potentially a lot of time spent running the engine at less than optimal operating temperature, and 300 heating cycles. If the outboard owner racks up his runtime hours in half hour chunks, that's 200 heating cycles for the oil, and I'd argue that the outboard spends more time at operating temperature where water is cooked out.

    Point being, I think there is a whole lot more to the discussion than "the outboard is run at a higher speed and power output over its oil change interval than the minivan and therefore needs special oil", particularly when nobody seems able to quantify what's so special about the special oil. "Contains compounds that fight corrosion" doesn't cut it for me...what are they and what do they do?

    As for the engine that spends its career sitting between a foot and three above saltwater, I say...So what? Is that water wicking up into the crankcase through the exhaust somehow? Is salt magically teleporting itself into the crankcase? It can't get there via evaporated water. Is this any different that the car owner who lives in a characteristically humid coastal area?

    I don't mean any of this to be argumentative, but if you're going to make a strident recommendation, snootily dismiss the alternatives, and make backhanded smartass insults, in this case it would be a good idea to have some sort of scientific, technical basis for your recommendation. Heresay doesn't work.

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    Member spoiled one's Avatar
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    I say "run with what you brung". I used yamalube for the first couple of hundred hours and have been running the marine amsoil for 4-stroke outboards for the past few hundred. I like it and will continue to run it. If it turns your crank to run the less expensive stuff that you buy from costco, great! The extra amount of money I spend on lubrication (for my twin yammies) is nothing compared to the amount I spend on boating each season. Heck, I will be running the amsoil in my F15 used on my tender just because I can. Less than two months and you all can go out and chase some shrimp. I will wait for May...because I can.
    Spending my kids' inheritance with them, one adventure at a time.

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    Marine grade, for me.

    But I'm persnickety and wasteful when it comes to oil. I buy the best and change it often. I'm no mechanic, but I still firmly believe that having the proper amount of clean quality oil in a motor is the single best thing you can do to make that motor last forever.

  19. #19

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    I talked to a couple of OB mechanics at the boat show last year 2 different ones. They both told me they had seen cases of std 4 stroke oil causing corrosion problems. I use oil that specifically rated for 4 stroke outboards.

  20. #20

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    I would love to know how oil could ever cause a corrosion problem. It is really beyond me that is the conclusion a mechanic would come to. I'd love for someone to chime in and explain it as there has to be some chemistry to do it. Again, I am no lubrication expert, but if there was something in auto oil that corrodes, it would corrod the heck out of the cars and trucks we drive too as the exhaust is a toxic brew that corrodes and reacts. When this gets past the rings it causes real trouble. And when it does get past the rings hence the change interval, it causes serious pitting, rust, sludge, and other trouble. In an environment where things may never really warm up (like in our boats), or like in the winter in your suv, things can get pretty bad down in there. The change interval becomes hyper-critical.

    But, I do concede that marine grade would be better if it has some more anti-corrosion and sludge additives in it. I am not sold that is has better lubrication properties through as commuter cars go through hell on a daily basis as do taxis, trucks, and other machinery. They run in blazing hot deserts, the frigid tundra, in incredibly wet areas full of humidity, in the dirt and the dust. They idle for hours, start and stop constantly, and in many cases, suffer serious neglect. In fact, many of the conditions that an automotive application goes through is far worse than anything my twin hondas goes through. It is pretty amazing to me that folks are implying that automotive grade oil really isn't that good.

    Of course, they are right. It is unbelievably amazing.

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