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Thread: Synthetic oils in engines...yes/no?

  1. #1
    Bad Karma
    Since my rebuilds, I'm slowly crawling toward the 20 hour mark, and I'm going to change the oil at that time.
    I've had lots of success with synthetic oils in my personal vehicles (anything from a Dodge Ram to a fully prepped BMW race car). I know there are plenty of opinions (informed and otherwise) out there, but I'm looking for some scientific evidence as to why I shouldn't run something like 20W50 Amsoil Race oil in my engines (twin 350 Magnums, with camshaft, intake, exhaust and valve work done).
    Boat spends all it's lifespan on the great lakes (mostly Georgian Bay and Lake Ontario), and water temperature is generally high 40's to mid 50's.
    Any ideas?

  2. #2
    I've been running full synthetic 20W50 oil in my 454 mag since it turned 100 hours. Now have 300 hours on it without any problems at all. Doesn't burn much oil at all even with Forged pistons.
    One thing I have noticed versus the strait 40W conventional oil I used before is the oil pressure is higher with the synthetic under all conditions, even after a long hard speed run.
    I think the oil pressure remains higher due to 2 factors. 1) The oil stays cooler), 2) the synthetic oil doesn't breakdown as fast under the extreme conditions a boat operates in.
    I would wait a while before converting to synthetic if you decide to convert. You want to make sure you motor is broken in completely. Not sure of the recommended hours but I waited until 100 hours.

  3. #3
    Question !!!
    How do you get your engine(s) up to operating temp when the water is so cold !!
    I guess thats one way tho' to keep the Boat beverages cool !
    Anyway, I always thought that synthetic oils advantage was :
    1.a resistance to foaming (causing starvation of oil to internals) at high rpm 2. resistance to breakdown due to heat
    3. slightly more "slippery"
    At this time (10 hours:
    1. no high rpm should be used ! yet
    2. Your engines gotta be running cold, so is heat (breakdown) a problem??
    3. You don't need/want the "extra slippery" when trying to break in an engine. Your rings could loose their seal at this point & glaze the cyclinders.
    4. Do you really abuse the engine enough to warrant $10.00 a quart for oil?
    Use a good blend & change it more often if worried about breakdown. Just my .02 http://free.*** http://free.***

  4. #4
    No Limits !
    Presently have a 23'-'99 Wellcraft Excalibur which I bought new (leftover model) Feb. of 2000. Was using Mercruiser oil and had a very high consumption rate since first bought boat. Used about a quart every 3 hours no matter how I ran it, easy or hard. At about 30 hours, switched to Mobil 1 15wx50w.which I use in everything else I own, truck, Valykarie,car, the works. Presently have 50 hours, change oil end of year and might be right above add oil mark when I change it. Very positive results with Mobil 1. Don't know if break in is required any more with Mobil 1 cause Porche and BMW both use 5wx30w in their cars from the factory. I hear Royal Purple is good also, but have only used Mobil 1. ( Guess cause I work for ExxonMobil Refinery in Louisiana) Hope the helps, but it's only my experience.

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