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Wrong engine oil!

Discussion in 'Catalina 310' started by marchem, Dec 10, 2017. Add this thread to a FAQ

  1. marchem


    Joined Nov 16, 2012
    612 posts, 59 likes
    Catalina 310, 2000, #31
    US Santa Cruz
    Changed the engine oil and filter today (25XPB, 2200+ hours). Getting easier to do. While writing up what I did I suddenly realizes that I had put gasoline engine oil (5-30) in, rather than diesel oil (10-40). I'm hoping that all I need to do is change it (again), this time with the correct oil. Any other issues? Any point in changing it twice?

  2. justsomeguy


    Joined Feb 20, 2011
    6,244 posts, 766 likes
    Island Packet 35
    US Tucson, AZ/San Carlos, MX
    I think you'll be okay.



    Joined Jun 15, 2012
    389 posts, 23 likes
    Hunter 50 AC
    US Greenport, NY
    I would change it once.

  4. Roland5048


    Joined May 12, 2004
    1,023 posts, 287 likes
    Hunter Cherubini 30
    US New Port Richey
    For your piece of mind, just change it then quit fretting over it. Life's too short to sweat the small stuff.

  5. jssailem


    Joined Oct 22, 2014
    5,541 posts, 1,836 likes
    CAL 35 Cruiser
    US Salem, Moored Port Everett WA
    Rob it is not a catastrophe... It will be great for winter time. You might consider change before next mid summer. On the other hand you be on the Pacific ocean in Northern Cal. You should be ok...

    What Is the Difference in 10w-40 Car Oil and 5w-30 Oil?

    by Harry Havemeyer
    Motor oil provides the necessary lubrication for an engine's moving parts. The oil acts as a lubricant that allows the pistons to move in the engine block without creating excess wear. The Society of Automotive Engineers, or SAE, classifies oil by viscosity and engine manufacturers provide a recommended motor oil viscosity for use in a particular engine. Mileage and weather can dictate adjustments in the proper viscosity of motor oil used in an engine. The difference between 10w-40 and 5w-30 motor oil is in the ability of the oil to cling to the engine's moving parts, which dictates the best application for each type of oil.
    First Number
    The first number in the motor oil's name describes the oil's cold viscosity. Cold viscosity refers to the thickness of the oil upon a cold start of the engine, before the pistons and engine block have warmed up from ignition and combustion. Motor oil's cold viscosity is important because it dictates the lubrication during the hardest part of the combustion cycle, the startup and initial ignition in gasoline engines or combustion in diesel-fueled engines. A 10w-40 motor oil is a thicker oil at startup than a 5w-30 motor oil. Therefore, 10w-40 oil clings to the engine's moving parts more than the lower viscosity 5w-30 oil.
    Second Number
    The second number in the motor oil's name describes the viscosity of the oil when the engine is warm and the oil reaches operating temperature. This warm viscosity is always going to be heavier because the engine requires a higher viscosity oil to provide ample lubrication through the broad range of the engine cycle and temperatures. The 10w-40 motor oil clings to the engine's moving parts more than a 5w-30 motor oil does at higher temperatures; this means the 10w-40 is the thicker of the motor oils when the engine is running.

    JamesG161 likes this.
  6. chuckwayne


    Joined Mar 20, 2004
    1,400 posts, 35 likes
    Hunter 356 and 216
    US Portland, ME
    diesel oil has a different additive package from gas engine oil and is blended to better match the characteristics of the diesel. change it (once) and then forget about it

    FastOlson likes this.
  7. kloudie1


    Joined Nov 6, 2006
    7,845 posts, 518 likes
    Hunter 34
    US Mandeville Louisiana
    As Chuck says, diesel oil has different additives to control blowby products (a diesel engine generally has more blowby than a gasoline engine) and to hold gunk in suspension until it can be purged. There is no rush to change out the 5W30 but sometime in the next 10-20 hours would be fine. No need to double change..

  8. jviss


    Joined Feb 5, 2004
    2,583 posts, 253 likes
    Tartan 3800
    US Westport, MA
    The weight is not so much a gas v. diesel thing, as is the additive package. For gas, look for service specs starting with the letter "S," for diesel, "C."

    This, from the Westerbeke (Universal) website:

    What type of oil should I use in my Westerbeke or Universal engine/generator?
    Use a well-known brand and try to use the same brand each time you change the oil. Avoid mixing brands of oil. Different manufacturers use different additives, and mixing brands may cause a problem if additives are not compatible. More important is to use the correct A.P.I. (American Petroleum Institute) and S.A.E. (Society of Automotive Engineers) ratings. For Westerbeke and Universal DIESEL models use A.P.I. code CF or CG-4, S.A.E. #30, 15W-40, 10W-30 or 5W-40. For Westerbeke GASOLINE models, use A.P.I. code SJ, S.A.E. #30, 15W-40, 10W-30 or 5W-40.

  9. marchem


    Joined Nov 16, 2012
    612 posts, 59 likes
    Catalina 310, 2000, #31
    US Santa Cruz
    Thanks. I figured the additives were an issue. I wasn’t too worried about the viscosity difference. Sounds like an easy screw up to recover from.

  10. jviss


    Joined Feb 5, 2004
    2,583 posts, 253 likes
    Tartan 3800
    US Westport, MA
    I wouldn't even be concerned about running it for a season, and then going with "diesel oil" next time.

    Are you planning on trashing the new filter, too, of you change it?

  11. Benny17441


    Joined May 24, 2004
    5,384 posts, 308 likes
    CC 30
    US South Florida
    A film of oil prevents metal to metal contact between moving components, mainly between crankshaft and bearings and piston rings and cylinder walls. The tolerance to what the components were designed and manufactured dictates the necessary oil viscosity. 5W-30 is a little thin for the Diesel engine specifications and could likely result in oil burning, a slightly elevated running temperature and low oil pressure. Go ahead and change the oil and I would recommend a grade of 15W-40. Any small amount of oil left in the crankcase will be diluted into the thicker oil. I would not worry about having done any damage or that any residue would inflict any in the future. I once had a ruptured lift pump diaphragm which leaked diesel fuel into the crankcase and the result was an oil so thin that made 5w-30 seem like molasses. I first heard an unfamiliar clatter in the valve train which led me to check the oil level which was really high and rubbing the oil between thumb and forefinger confirmed it had lost most of viscosity. Long story short replaced the pump and changed the oil with seemingly no lasting ill effects. Another thing that can degrade viscosity is excessive heat; any time the engine overheats it is recommended that the oil be changed. Your mistake was not that serious.

  12. jviss


    Joined Feb 5, 2004
    2,583 posts, 253 likes
    Tartan 3800
    US Westport, MA
    The manufacturer recommends:

  13. Michael Davis

    Michael Davis

    Joined Jan 5, 2017
    567 posts, 224 likes
    Beneteau First 38
    Ca Lyall Harbour Saturna Island
    Diesel generally has more E.P. additive for the higher compression engines i was told. I would change the oil before running it if it were mine. Save the worry.

  14. marchem


    Joined Nov 16, 2012
    612 posts, 59 likes
    Catalina 310, 2000, #31
    US Santa Cruz
    Filters are relatively cheap. I've always changed filters and oil at the same time, car or boat.

  15. JamesG161


    Joined Feb 14, 2014
    2,741 posts, 749 likes
    Hunter 430
    US Waveland, MS
    I have been using a synthetic Oil for 2 seasons. Last I researched the differences, the "C" rating is now "J" only because of the contaminant removal for diesel rigs that run the highways.

    It has to do with lowering the Sulfur content of refined diesel oils.
    You can actually blend your own range of so called "weights" of Lube Oils.

    I use 5 quarts of this...
    and 1 quart of this...

    To cover the recommended Viscosity Range of my Volvo Penta 50 hp, at my warm water operating temperatures along the Gulf. [mine starts faster than my Ford Expedition gas engine]

    With the synthetic, I have reduced Carbonization as proven by my used oil color and cold start smoking.
    As to refined diesel oils...
    Oil Sulfur content for engine longevity has not been shown to be a factor.

  16. Stu Jackson

    Stu Jackson

    Joined Feb 26, 2004
    19,846 posts, 531 likes
    Catalina 34
    224 CA Maple Bay, BC, Canada
    Rob, remarkably consistent responses. I think you've set a record for the forum! to share just HOW you did this???:):):)

  17. jssailem


    Joined Oct 22, 2014
    5,541 posts, 1,836 likes
    CAL 35 Cruiser
    US Salem, Moored Port Everett WA
    So you young guns with your turbos and shiny new Beta/beake/saildrive/Yama jammers it seems easy to read the newly minted manual and get the engineering wisdom to buy the current knowledge about oil for your diesel.

    What are your ideas regarding an old 1973 work horse, built like a timex watch. It takes a licking and keeps on ticking. The design was to fuel with diesel based on the 1940’s standards. Sulfur was a prime ingredient, and oil came standard weight.
    Where the manual says
    0-30F 10W. 30-80F 20W. and Over 80F 30W
    From companies like. A. Duckham Co Ltd and Total Oil Co Ltd. which featured “Total Super Universal Tractor Oil (Multagri TM)”
    Which unfortunately is not among the brands featured at the local WM or Marine Chandler.

    What’s a hip young boat owner to do?

  18. FastOlson


    Joined Apr 8, 2010
    945 posts, 89 likes
    Ericson Yachts Olson 34
    US Portland OR
    Well, don't be defensive about your older diesel, for starters! :)
    Or, are you just trying to wind us up. (LOL)

    It's older than my engine, but they are more similar than they are different.

    I know of a diesel mechanic with 40+ years of experience and he advises that when my engine was built the engineers specified the oil that was being formulated at the time. Decades later there are different and better products on the market. So I use Delo 400, 15-40 weight. My historic original engine manual specifies 30 weight for my 1988 engine, and that was and is fine. But things change.

    Shop around, too. West Marine is handy when you need something on short notice, but you can usually fine oil quite a bit cheaper elsewhere. Also, WM is slowly backing out of the chandlery business.... few more years and the transition to clothing, fishing gear, and SUP stuff will be complete! :(

    Fair winds.

  19. JamesG161


    Joined Feb 14, 2014
    2,741 posts, 749 likes
    Hunter 430
    US Waveland, MS
    Remember those are COLD START temperatures.

    My engine cooling runs at 180°F after the thermostat kicks in. Even in cold weather, here on Gulf, where the cooling water is seldom below 60°F, even in the rivers.

    Here, according to those above numbers, I want 20W! Forget the Multi Range oils.:clap:

    BTW, I don't blend for my 16hp Yanmar genset diesel.

    PS: I just read the Shell Rotella synthetic specs. They claim better Oil aeration. Say What?:confused:

  20. jssailem


    Joined Oct 22, 2014
    5,541 posts, 1,836 likes
    CAL 35 Cruiser
    US Salem, Moored Port Everett WA
    I read that as well. Seem to recall from shop class that oil aeration was a no no...

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