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Conference vicki::boats

Title:Powerboats
Notice:Introductions 2 /Classifieds 3 / '97 Ski Season 1267
Moderator:KWLITY::SUTER
Created:Thu May 12 1988
Last Modified:Wed Jun 04 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:1275
Total number of notes:18109

79.0. "Unleaded vs.Leaded:MarineEngines" by HAZEL::YELINEK (WITHIN 10) Mon Jul 18 1988 13:33

    Whats the deal concerning the use of UNLEADED fuel Vs. LEADED??
    
    It was my turn to top-off my buddies boat prior to going diving
    this past weekend and I noticed there was NO Unleaded at this
    particular gas dock (perhaps all). There was only REGULAR & DIESEL.
    I asked the attendant concerning the use on Unleaded and he said
    that when the LEADED gas is phased out the marinas will receive
    Unleaded Fuel with 'some type of ADDITIVE. ?? 
    
    Now I understand that perhaps the older gas engines might not like
    guzzling the Unleaded as the UNLEADED Fuel burns HOTTER (but cleaner) 
    and also lacks the lead which does provide some degree of lubrication. 
    But what about the newer engines?? say 1977 to date. (I'm guessing
    the date when the automobile engines began the use of unleaded gas.)
    
  > Haven't the engine manufactures began designing in the use of engine
    components that are able to run solely with UNLEADED FUEL? Since,
    after all, most consumers known that Leaded Fuel will be phased
    soon.
    
  > Is there some 'magical additive' that will be mixed with the Unleaded
    Fuel for todays gasoline engines vs. designing the engine around
    the Fuel Available?
    
    MArk
                                               
    
T.RTitleUserPersonal
Name
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79.1Marine engines <> Automobile enginesTOMCAT::SUTERWater is meant to ski on!Mon Jul 18 1988 13:367
    
    
    	My 1987 351 PCM is supposed to run REGULAR (the kind with lead)
    but getting it is a different story in Effingham, NH! I'm told
    that places like Bradley's sell lead additive, anyone seen it around?
    
    Rick
79.2Run what you have best access toHJUXB::GUSTAVSENMon Jul 18 1988 14:1117
    
    	I have a 1984 120Hp Mercrusier. When I purchased the boat I
    asked the dealer if I should run Leaded or Unleaded. He told me
    that the engine could run either one, but I should stick to one
    or the other. The reason being that the engine would need to be
    retuned differently going from one to the other. I have found that
    a change in the engine timing would have to be made by about 3-5
    degrees to accomodate the fuel change. Since I have purchaced the
    boat I have always run Premium Amoco Unleaded, and have had no problems
    with it at all. Also a friend of mine had purchased a 87' Bayliner
    with a 120Hp OMC and was told the same thing by the dealer. You
    can run Unleaded or Leaded the dealer says, as long as to change
    the timing to accomodate the fuel change.
    
    		Dan
    
    
79.3Getting the lead BACK IN !MENTOR::REGPointing fingers often backfireMon Jul 18 1988 14:267
    re .0	I've seen additives for that,  "Re-lead",  or a similar
    name.  I think I saw it at Marine USA (ex Doug Russell's) only this
    saturday.  I've also heard that Marvel Mystery Oil will help engines
    to run cooler and not knock {4oz/10 gallons}, though I have no "data".
    
    	R
    
79.4Engines are built to handle the change...BINKLY::SMITHMon Jul 18 1988 14:5012
    
    I have been told that engine manufactures have known about the fact
    that REGULAR leaded gas is going to be phased out and they have
    made the necessry changes to the engines to accomodate the lack
    of lead in the fuel.  I have also been told what the others have
    mentioned about TRYING to use one or the other consistantly.
    
    I would say you can't hurt the engine if it is not real old, but
    it may run better because it is adjusted for one type over the other.
    
    /Mike Smith
    
79.5Engines have Harden ValvesMYVAX::ONEILLMon Jul 18 1988 16:4813
    
    	Since the mid 70's, engines have been manufactured with HARDEN
    VALVES. These valves can withstand the higher burn tempertures you
    get with un-leaded fuel. Lead provided some lubrication and cooled
    the burn tempertures. Today's leaded gasoline contains very little
    lead. Using a higher octane gas will help minimize engine knock,
    (In some cases timing may need to be changed). So engines that were
    manufactured before the Mid 1970's were not manufactured with harden
    valves and will have problems with un-leaded fuel. If the information
    is still there, this topic was dicussed in the carbuff notes file.
    
    
    	Mike
79.6TOMCAT::SUTERWater is meant to ski on!Mon Jul 18 1988 16:538
    
    	RE: .5
    
    		Yup that's the problem... PCM either can't get
    an answer or the answer is NO from Ford on the 351s having
    hardened valves.... yes even in 1987!
    
    Rick
79.7Hello, Yamaha?BTO::JPETERSJohn Peters, DTN 266-4391Mon Jul 18 1988 18:2120
    My '81 Mercury V150 outboard requires leaded gas with a minimum
    specified octane per the user's manual.  It is, of course, a 2-stroke,
    so there are no valve seats to be concerned about, but I believe
    that the lead helps prevent piston skirt scuffing, and I suspect
    it may help the needle and roller bearings somewhat.
    
    I wrote to Mercury last year and got a non-answer, to the effect that
    they offered no detuning instructions or parts, and that I should use
    unleaded whether it's available or not. 

    Based on this interaction and a few exchanges around parts, I won't
    be buying Mercury the next time I'm looking for an engine.
    
    John
    
    Note that this blows the assumption that if it's manufactured after
    the mid '70's it'll be designed for the newer fuels.  It costs money
    to redesign and retool, and American industry has never been noted
    for flexibility and intelligent planning.
    						J
79.8If PCM & Indmar don't know, who does ?MENTOR::REGJust browsing; HONEST, I'm BROKE !Mon Jul 18 1988 18:447
    re .6	Hmmm, somehow I thought that Marine'izers knew it all
    about the engine's guts, ESPECIALLY the HEADS.  Now I'm wondering
    what their contribution is, other than stainless steel head and
    other gaskets to handle salt water....
    
    	R
    
79.9OutboardsDIXIE1::WILKINSONMelted Snow SkierMon Jul 18 1988 18:578
    Most recent word from Johnson/Evinrude is use leaded 87 octane for
    75 HP and down and 89 octane leaded for 80 HP up.  If leaded is
    not handy you can use 87 unleaded for 75 HP and down but not for
    80 HP and up.
    [from Clymer's Shop Manual for Johnson/Evinrude]
    
    Nelson
    
79.10What's an '87 octane?SETH::WHYNOTMon Jul 18 1988 19:4615
    Indmar engines have hardened valves and valve-seats. When I called
    their tech support number to ask if I should use leaded or unleaded,
    I was told "it doesn't matter", Which is better?, "it doesn't matter"
    You know what I found?...It doesn't matter. I either run super
    unleaded, at 92 octane, it seems to warm up better on those cool
    damp mornings, also because I feel better about not putting lead
    in the lake. But, if I'm scrounging for pennies for boat gas, I
    will use leaded regular at 89 octane because its' cheaper.
    I don't use reg unleaded, not even in my lawnmower.
    BTW: Mine is the Chevy 350 4-bolt (model 300 SP) that has, what
    look like, water cooled headers, (brushed aluminum finish) as
    opposed to the "pyramid exhaust" that PCM and Mercruiser use.
    These are so cool you can put your hand on them, and hold it there,
    at operating temperature. This engine should last quite a long time.
    Doug.
79.11dunno where I pick this stuff up....MENTOR::REGJust browsing; HONEST, I'm BROKE !Tue Jul 19 1988 11:587
    re .6	It sez 'ere 93 octane rating (Research Octane Method)
    minimum, but I'm still trying to figure out how *_I_* came to be
    in possession of a PCM booklet/spec sheet/ Awright, its a damned
    sales flyer :-^)
    
    	Reg
    
79.121985 Force O/B uses UnleadedFSDEV1::BSERVEYBill ServeyTue Jul 19 1988 18:406
    My handbook for a 1985 85 HP Force (aka Mariner, aka Chrysler) has
    the following recomendations:
    
    1st Choice: Unleaded Regular (87 Octane)
    2nd Choice: Unleaded Hi-test (89+ Octane)
    3rd Choice: Leaded Regular   (83? Octane)
79.13Who makes what?TOOK::SWEETCapt Codfish...Looking for Mr. TunaTue Jul 19 1988 18:508
    re: force aka mriner aka chrysler
    ??
    I thought mariner's were mercs and force were chryslers. I am not
    talking labels or owners I am talking actual parts and manufacturing.
    
    Anyone go the real scoop?
    
    bruce
79.14Family TreeNRADM::WILSONYou have my word on it...Tue Jul 19 1988 19:4137
RE: .13
 >> re: force aka mriner aka chrysler
 >> ??
 >> I thought mariner's were mercs and force were chryslers. I am not
 >> talking labels or owners I am talking actual parts and manufacturing.
 >> Anyone go the real scoop?
   

Bruce,

Force is owned by U.S Marine. They bought the entire Chrysler line
and tooling. Before Chrysler they were known as West Bend.

The larger Mariners are built by Mercury. As I understand it the smaller
Mariners are built by Yamaha. There is also a new line sold under the
name of Sea Ray, which are actually Merc's painted white.

Just to confuse the issue, U.S. Marine is now owned by Brunswick, which
also owns Mercury, making Merury and Force first cousins.
 
As you are probably aware, Brunswick and OMC have purchased many of the
major boat manufacturers within the last couple of years. An interesting
point is that when Brunswick purchased Bayliner 2 years ago, they were
in the embarassing position of being under contract with OMC to supply
stern drives for Bayliner boats. The contract has since run out and
Bayliners are now built with Merc sterndrives.


                BRUNSWICK                       OMC
               /        \                       |
    U.S. MARINE         MERCURY                 |-JOHNSON
    |-FORCE             |-MARINER               |-EVINRUDE
                        |-SEA RAY               |-OMC SEA DRIVE


Rick W.

79.15I almost remembered correctly!ODIXIE::WILKINSONMelted Snow SkierWed Jul 20 1988 15:0943
    Well, I almost remembered all the facts from memory but it was somewhat
    corrupted.  Here is the corrected posting to my previous reply straight
    from the book:
    
    "	In the past, Evinrude and Johnson have reccommended the use
    of regular leaded gasoline with a minimum posted pump octane rating
    of 87 (50-75 hp and V4) or 89 (V6).  However, obtaining regular
    leaded gasoline with an octane ratign that high is becoming extremely
    difficult.
    "	For this reason, OMC factory engineerign issued new fuel
    reccommendations in March 1983 for 1977 and later models (no mention
    of a change for  1973-1976 models).  Unleaded regular or premium,
    leaded regular or premium or gasohol with a minimum octane rating
    of 86 is now reccommended for 50-115 hp engines.  Only regular or
    premium leaded gasoline with a minimum octane rating of 88 is
    recommended for 140-235 hp engines.  Lead-free gasolines should
    NOT be used in 140-235 hp engines regardless of their octane content.
    "	Owners of 70-200 hp models can obtain a low octane modification
    kit from the Johnson or Evinrude dealers if the recommended gasoline
    is not available in their area.  Installation of the kit will permit
    the engine to be operated with a lower octane gasoline or with
    gasohol."
            [from Clymer's Evinrude/Johnson Outboard Shop Manual (50-235hp
    	     1973-1987)]
    
    For the 1988 Model Evinrude engines:
    
    "	Fuel facts:
    All 1988 Evinrude motors can use lead-free gasoline, leaded regular
    gasoline or gasoline with up to 10% ethanol or up to 5% methanol
    with 5% co-solvents, so long as the fuel is at least 87 octane for
    motors 40-V8 (300 hp V8 drool, drool!) and 67 octane for motors
    Junior-30, mixed with Evinrude TC-W outboard lubricant."
    
    [From 1988 Evinrude sales stuff]
    
    Just a side note: the Evinrude catalog has a picture of a open
    Wellcraft with twin counter rotating 300 hp V8s on the back end
    with power steering.  Maybe for Christmas?
    
    
    Nelson
    
79.16Cut up the sinkers and throw em in the fuelAD::GIBSONRainbow Chaser dtn 225-6501Wed Jul 20 1988 18:4914
    No,No, Not a Cry-slur!  I used to own a Marinr Dealership and for
    sure they are a mongrul between Merc's and Yamaha's the line is
    split a bit differnt each year, but the big motors are merc/Mariner
    
    The whole world will soon be owned by Brunswick.
    
    Whatever happened to Elgin, or Buccuneer, or ole's or Allstate or
    ??????
    
    Yes help! A test was run recently with a 454 chevy marin engine
    buy mercruiser and it blew up with less than 40 hours without lead!
    
                                Walt
    
79.17Mix the gas, oil, and lead before ignition...NETMAN::BAERGarry BaerWed Jul 20 1988 20:5719
	I used to have a 175hp Merc outboard (1978) vintage.  I used the
highest UNLEADED octane gas I could find (SUNOCO 93.5) and then mixed it
with REAL LEAD per the instructions.  The current LEADED gas you can buy
at the pump is NOT desirable for the following reasons:

	1) the lead content was dropped last year from .005 to .001 %
	   It has been dropped several times this decade.  Not acceptable
	   if you have an older motor and want to keep it lubricated well.

	2) The octane is 87-89.  My motor was spec'ed for 93.  Clearly I 
	   could de-tune it, but that doesn't make much sense.  We now
	   have the technology to make a 175hp into a 150hp?????

	I used this mixture for the last 4 years and my motor purred like a
kitten.  The several times I had to adlib due to the lack of READ LEAD, 
the performance dropped off noticably.  Wel worth the effort to get the
performance you payed for.

	Garry
79.18Alcohol+lead=ProblemsUSRCV1::FRASCHFri Jul 22 1988 13:2213
    Right on!! LEADED gas doesn't have much lead in it. They do, however,
    add ALCOHOL to increase octain ratings. A problem---alcohol will
    break down older fuel lines and cause them to leak!!!! Check those
    lines from the tank to the pump to be sure they are soft and pliable.
    If they are not, replace them aith a new USCG "alcohol resistant"
    fuel line. You can get them at any marine dealer (cheap).
    
    This can also cause problems with fuel pump diaphrams. If the "clear"
    line from the pump to the carb has cas in it, CHANGE THE PUMP FAST!!!!
    
    Good luck
    
    Don
79.19SMAUG::LINDQUISTFri Jul 22 1988 14:146
79.20Mercury 1988 takes bothHSK01::LUPANDERJan-Christian LupanderMon Aug 01 1988 14:0812
    Re Mercury outboards: The manuals for my V200/1988 states that both
    leaded and uleaded are acceptable. (86 octane minimum)
    The "Service assistance and Warranty Information" booklet however
    after stating roughly the same adds as a last line:
    "For optimum performance of higher horse power models we recommend
    the use of premium(super) unleaded gasoline."
    
    That booklet as well as the users manual repeatedly warns about
    the possible problems (ref .18 and .19) arising from using alcohol/gas
    mixtures.
    
    -jcl 
79.21No change for OMC 120hp motorHJUXB::BIANCOWed Aug 03 1988 19:4917
    RE .2
    
    Dan is correct in stating that you can use either leaded or unleaded
    in the OMC I/O's with a reduction in timing except for 1 motor,
    the 120hp.  I recently got my boat back from the dealer and the
    boat could not get out of its own way.  After talking to the OMC
    specialist directly he informed me while it is true that most OMC
    motors require a reduction in timing, the 120 hp motor requires
    no change and can run either flavor.  Sure enough I went home and
    checked the timing to find it reduces 5 degrees.  A simple turn
    of the wrench, back up to 10 BTDC and the boat has new life.  No
    problems running unleaded for 2 years now and plugs and points wear
    very nicely thus far.
    
    
    Bob
    
79.22Tune or de-TuneNETMAN::BAERGarry BaerWed Aug 03 1988 20:3015
	Which was should you set the timing for what type of gas??  Could
someone in the know let us know?

	Unleaded -> retard x degrees

		or

	Leaded -> retard x degrees

	I ahve a 1988 OMC 5.7L I/O and the dealer said that either was fine
but they usually use high octane UNLEADED.  Any other OMC V6 V8 users out
there with personal performance tests & results?

		Garry
79.23Unleaded = reduction in timingHJUXB::BIANCOThu Aug 04 1988 20:2714
    Garry,
    
    	Not sure of the exact octane ratings for your motor, but the
    service guy is right in telling you to use high octane unleaded
    fuel.  The service manual for your motor tells you exactly what
    is needed and how the engine should be set up for each type of gas.
    	To answer your question, unleaded fuel requires a reduction
    in timing on most OMC motors, as told to me by the OMC hotline.
    The service manual and parts manuals are great to have around. 
    The back of your operators manual should have the order form for
    both.  
    
    Bob
    
79.24The dealer told me to use *leaded*!JACKAL::SNOWFri Aug 05 1988 11:3113
    
    	I've been following this note with some interest, mainly because
    what has been said for the most part doesn't agree with what the
    manual and dealer told me about my boat. I bought a 16.5' Larson
    with Mercruiser 120 I/O last July, and both the dealer and the manual
    reccommend _leaded regular_ gasoline! The reason I was given was
    that the alcohol additives in unleaded would attack the fuel line
    fittings, plus be more susceptable to condensation in the tank.
    Is there some truth to this, or was I being lead down the garden
    path?
    
    Dan
    
79.25octane vs timing...NETMAN::BAERGarry BaerFri Aug 05 1988 17:1925
RE .23

Bob,

	Thanks for the info.  My 5.7L states that I should use 89/93 octane
(new/old rating method).  The reason I asked is my motor did not seem to
WANT to open up.  I have it prop'ed correctly (19" std-type blades) but cannot
get it over 3900-4000 RPM.  It could be several things I just have not had the
time to look at it.  It goes in for its 20hr checkup next week and after that
I will be on Vacation (Sebago).  That will give me some "spare" water time to
play around with a few things (throttle linkage, timing, etc).  It had got to
be something simple because the motor does not sound overloaded, just not
opening up.  murphy's law state that if the Marina cannot find *anything*
wrong with it (RE: Jeanne's problems) it must be easy to solve by someone
not in the industry!!!

	BTW, anyone planning on being at Sebago the week of the 14th or 
the 21st??  We are part of a 3 boat vacation and will be chewing up some
serious distance on water as none of us have had much floating time this
year (new families and all...).  If so please send mail to NETMAN::BAER
and we could have a mini GUMBALL of our own (hello Dan).

	Cheers

	Garry
79.26tuneup in a can?PENUTS::GORDONMon Apr 06 1992 16:1221
    The subject of this note looks close enough, if not Mr. Moderator
    please move it.
    
    I was talking to the dealer that I bought the 150hp Mariner a couple
    years ago.  He recommended that I run a can of "engine tuneup" thru the
    engine to remove carbon.  I has read something about this regarding OMC
    engines in a BOAT US flyer.  Apparently with the reduction of lead in
    gas outboards are having carbon build up problems.
    
    This "tuneup" is used like a fogging oil.  Spray it into the engine,
    let it set for 1/2 hour and then run the engine at full throttle for a
    period of time.  This stuff is supposed to loosen the carbon and then
    burn it off.  What I read was that the carbon gums up the piston rings
    and causes them to stick.
    
    Has anyone used this product?  What were the results?  Any cautions,
    etc.
    
    Thanks,
    Gordon (pulled the cover this w/e and started the spring work)
    
79.27I use itLEVERS::SWEETMon Apr 06 1992 16:236
    I always use a can of OMC engine tuner when I lay up in the fall.
    Certainly hasn't hurt as the boat turns over as soon  as gas
    makes it into the cylinders in the spring (which it did last friday,
    now if the damn wind ever stops blowing....)
    
    Bruce
79.28The key is to avoid carbon buildupGOLF::WILSONMon Apr 06 1992 16:3526
    Gordon,
    With a few exceptions, 2 cycle outboard have *never* required 
    lead.  2 cycle outboards have no valves which require lubrication, 
    and the rest of the motor is lubed by the gas/oil mix. I have 
    documentation put out by Mercury in the 1950's that recommends 
    the use of "unleaded marine white fuel" for their outboards. 
    This was back when unleaded was hard to find, and they were 
    recommending it anyway.  
    
    Unless there's something I'm unaware of, there's no reason that
    unleaded gas should leave more carbon deposits than leaded and 
    require additional cleaning or de-carboning.  The lead itself 
    tends to leave deposits behind. Remember what spark plug life 
    used to be like in the 60's?  Plugs were caked with carbon and 
    lead after only 10-15K miles.  From what I've seen, motors that
    have been run only on unleaded tend to be cleaner inside, not 
    dirtier or more carboned up.
    
    So, if you use a 92 octane unleaded premium gas and the proper 
    mix of the best oil (OMC or Merc Quicksilver oil) *my opinion* 
    is that you should never have to worry about using a carbon 
    cleaner.  If carbon does exist, breaking chunks of it loose 
    and running it through the cylinders motor can sometimes cause 
    additional problems anyway.
    
    Rick
79.29PENUTS::GORDONMon Apr 06 1992 16:5918
    Rick,
    
    The article that I read in BOAT US flyer stated that this was becoming
    a problem with OMC outboards in the higher hP ranges with piston rings
    sticking.
    
    As for the 92 octane fuel, I keep my boat in a slip and there is no-one
    selling gas in Newburyport that offers a choice in octane ratings.  All
    they sell is regular (87 octane).  My only alternative is to carry it
    in 5 gal cans, no small task with a 60 gal tank.
    
    I have never been a big fan of fuel/oil additives, but at 5K+ for a new
    engine I want to take all the precautions I can.
    
    Could be that they just want to sell a new product.
    
    Gordon
    
79.30PingSALEM::GILMANMon Apr 06 1992 18:305
    I wonder about ping which can be caused by running unleaded fuel.  I
    don't know how you would hear ping in a OB anyway unless it was severe.
    
    Is it worth running 92 vs 87 octane on a regular basis in an engine
    which has 'no' ping problem you know of?
79.31piston stick in yam'sSMURF::AMATOJoe AmatoMon Apr 06 1992 18:3713
    re .29
    
    I've heard the same thing (piston sticking) about the large yamaha's
    from a prof marine mechanic.  He recommended using the de-carboner 2x a
    year.  Mid season and end of season.  He claims that there have been
    problems with the older (pre '90) yams' breaking.  I figure for $5/can
    x 2 cans/year, thats cheap insurance.
    
    BTW, if the pump reads correctly, the gas dock in Hampton only has 92
    octane and the price was reasonable.  I believe I was paying $1.37 last
    year.  
    
    Joe
79.32just another canCARROL::YELINEKWITHIN 10Mon Apr 06 1992 19:5810
    ...Hmmmm
    
    Wonder what YAMAHA did to the post '90 large outboards that may have 
    rectified the (piston sticking) problem.
    
    /MArk
    
    I use the engine tune(decarbonized) toward the end of the year just
    prior to pulling the boat.  Can't hurt to do it mid-season as well.
    
79.33Life's getting too complicatedDNEAST::OKERHOLM_PAUTue Apr 07 1992 11:3519
    	I also read the article from Boat US and I took note because
    outboards where included. I don't know why the carbon deposits 
    result from no lead but apparently they do.
    	I am a little skepticle about adding "stuff" to my fuel so I'd like
    some assurances that the Engine Tune is made for outboards as well as
    I/O's. There's a big difference between cast iron and Aluminum Alloy.
    Does it state that its recommended for both?
    	Regarding octane. Outbords are not high compression and therefore
    don't need high octane fuel to prevent knock. However, I was told that
    in most brands the Super Premium has more or better additives (detergent?) 
    for the purpose of keeping the engine clean. Here again I wonder if
    detergents designed for auto engines work well when mixed with oil and
    run in an Aluminum block.
    	As an aside, I heard or read (maybe it was the same article) that
    OMC has quietly backed off its claim that its smaller O/B's will run 
    on 100 to 1 gas to oil ratio. I was sceptical about that as well.
    Apparently warranty action has increased significantly.
    	Who says you don't need technical training to live in today's
    world?    ;^)
79.34me tooPIPPER::BORZUMATOTue Apr 07 1992 11:597
    
    I remember, also that i had heard or read the same thing
    about OMC outboards.
    
    Wonder what brought this on.
    
    JIm
79.35only $1.37 for 92octanePENUTS::GORDONTue Apr 07 1992 16:598
    re: .31
    
    Only $1.37 last year in hampton.  I paid $1.58 last year for reg at the
    bridge marina in Newburyport.  I'm off hampton a lot maybe I should
    stop in a fill up from now on.  I'll see if I can miss the the BIG rock
    just upriver from the bridge this time.
    
    Gordon
79.36Some of my commentsHDECAD::CHACEMy favorite season is getting nearer!Tue Apr 07 1992 17:4827
    
      The presence or absence of lead in gas has no bearing on ping by
    itself. What causes ping is spontaneous ignition of the gas/air mixture
    rather than a smooth burn as it is supposed to be. The connection comes
    from the fact that lead was always used as an octane booster which DID
    reduce the likelyhood of pinging. Only the octane rating matters when
    it comes to preventing ping.
    
    As far as worrying about using things in aluminum blocks: Most autos
    these days have aluminum blocks with steel sleeved cylinders, just like
    outboards. I know of no modern outboard that does not have a steel
    liner. One big difference between outboards and autos is the much
    greater presence of oil *above* the piston. This oil is
    superheated/burned off as the fuel/air/oil mixture burns. This can
    cause the top ring to get carboned up. It usually happens in the higher
    horsepower engines, but can happen in any give the right (wrong?)
    circumstances. I for one will follow the factory's recommendations and
    use their oil and hope for the best.
    
      As far as the compression ratio of outboards being small and so they
    cannot ping goes: there are a lot of factors that contribute to an
    engine's likelyhood of pinging, compression ratio is only one. Two
    cycle engine with 'low' compression have no trouble pinging under some
    circumstances. You do not want it to happen. They can not handle it as
    well as four cycle engines can.
    
    				Kenny