, and you are absolutely correct in what was reccommended in '75 is no longer relevant to todays motors or todays fuels. I listed it only as an example of how the reccommenations have changed over the years, another example would be spark plugs which have been superceded over time to compensate for the changing fuels and additives.<br /><br />This thread did get a bit side tracked didn't it. <br /><br />Mark42's information is correct in that it matches what I've been taught in Evinrude/Johnson service schools (i.e. 1995 EPA requirement for all fuels to have a minimum level of detergency). This brings out a couple of good points and one that needs clarification.<br /><br />If you talk with someone in Evinrude tech service today, they will tell you that unless you have a highly modified (racing), hi-compression engine 87 octane will suffice. They will however quickly add that the use of quality TCW-3 certified oils is mandatory. As explained to me, the recommendation for premium fuels was in fact, that they wanted the hi-detergency of the premium fuels, as these were the days before TCW outboard oils existed. The appearance of TCW-3 oil negated their requirement for premium fuels for most recreational boaters. There are several fuel and oil related OMC-produced service bulletins which discuss these topics. SB 2155 and 2159 discuss timing changes and other modifications that may need to be made to some 1985 and older models.<br /><br />And just like EPA minimum detergency levels for fuel, TCW-3 is a "minimum" level too. IMHO, the $5/gallon TCW-3 Brand-X oil is not as good as the Evinrude / Johnson XD-30 TCW-3 oil. <br /><br />I can only add my personal experience with higher quality oils, having previously owned a 1998 Ficht and now owning a 2001 Ficht (an engine which notoriously produces lots of sooty combustion chamber deposits). This engine began its service life on the Evinrude Ficht Ram oil (now called XD-50). Every fall when I winterize I use a bore light to inspect each cylinder. I have to say the 2001 engine with Ram oil was about 50% cleaner than the 1998 engine which I used regular Evinrude TCW-3. I was religiously using Carbon Guard in EVERY tank of fuel with both of these engines and ran a decarbonizing treatment (Engine Tuner) once a year.<br /><br />After 2 seasons of XD-50 use I switched over to the Evinrude XD-100 oil. I noticed after the first season of using XD-100, the cylinders appeared cleaner than I remembered from the previous year. And at last years winterization, I could once again see the part numbers the factory etches into the top of the pistons. <br /><br />Needles to say, I no longer use the Carbon Guard, nor use Engine Tuner. The expense of those products alone, offset the cost difference in the "best" oil available for my engine. I'll add I typically buy 87 octane and rarely buy premium, unless its the only available fuel (usually at the fuel dock).<br /><br />The price difference between regular & premium fuels in my area is about .30/gallon (and much higher @ fuel docks). That's about $12/tank for my boat. Depending on the type of outboard (2-stroke carbureted or 2-stroke DI) you own and your driving habits, it may be more cost effective just to buy the better oils, rather than the premium fuel.<br /><br />Will premium fuel "hurt" an outboard? - I doubt it. Is there any benefit to using premium? I think so, but I think the benefit is minimal if you use good oil.<br /><br />It doesn't hurt to buy your fuel from a name-brand hi-volume retailer either.<br /><br />Just some additional food for thought.<br /><br />-JohnJet fuel is equivilant of about 45 octane fuel..<br />It will ruin a piston engine in about 5 minutes at WOT....
<br />We had a youngster on the line fueling a/c here years ago, that mis-fueled a Cessna 421 with JA-2M (same as JP5 with anti-microbials) he aborted take-off roll and the left engine siezed before he could pull the throttles back all the way (power is reduced very slowly on these as to not shock-cool and crack cylinders). upon teardown (Manditory) of both engines, both were beyond specs and total junk...about 45 thousand a side mistake....Off topic, I know...just hope nobody gets an Idea to try this....
My 1964 Lightwin Manual says:
This is another piece of information that I have not found any substantiation for (other than members opinion).<br /><br />Again, higher octane does not cause problems. Claims of hotter burn and poor running are not the characteristics of high octane fuel. Almost across the board, high octane fuels just burn SLOWER, not hotter. Actually, the explosion of fuel known as "knock" is actually hotter than the normal burn temp of gasoline. The temperature of the burn is more influenced by combustion chamber shape and compression ratio than by the difference between regular and premium.<br /><br />And again, reduced wear is a benefit from premium because the additional cleaning agents keep carbon deposits down. It's those deposits that chew up the rings and cylinder walls every bit as fast or faster than using poor quality oil.<br /><br />And before someone jumps in with claims that 4 cycle tech does not apply to 2 cycle motors, please keep in mind that deposits occure in every interal combustion engine. Outboard 2 cycle motors were designed to run on gasoline, and benefit from premium fuels the same as any other motor designed to run on gasoline.<br /><br />Both regular and premium fuels contain the same BTU, so it is hard to imagine one will burn hotter than the other. Depending on your engine, if it has pre-ignition, premium will give you better economy because it will not lose power when pinging. For members with I/O or 4 cycle o/b this is a very real situation. I have never experienced 2 cycle pre-ignition, although I hear it will grenade a 2 cycle. <br /><br />Regarding the documentation of premium vs regular by OMC, in the 1993 owners manual it states... "NOTE: Use of premium grade fuels is specifically encouranged.... ...premium fuelds contain detergent and dispersant ingredients... ...these ingredients also remove and prevent carbon buildup on pistons and rings. These ingredients can extend engine life while maintaining a high level of performance." I'm sure OMC had proof of the advantages of running premium over regular to put that very specific suggestion to use premium in their motors.<br /><br />Just something to think about.
Found yer boat for the Jet fuel
<br /><br /> http://cgi.ebay.com/ebaymotors/1996...ewItemQQcategoryZ26432QQitemZ4600154658QQrdZ1
Originally posted by Dave Abrahamson:<br />Found yer boat for the Jet fuel
