Yamaha 9.9HP High Thrust Questions

[John from Madison CT]

Gents: Just got my Yamaha 9.9HP 4 Stroke, High Thrust via Ebay. I got a great deal, had it shipped via Fed-X freight, terminal to terminal for $142. (MI to CT)<br /><br /> The previous owner drained the lower unit and the engine oil, so I added it as specified.<br /><br />Question #1 : I bought regular Automotive Castrol 10W30. Is this OK, or do I need a Marine grade 4 stroke Oil ? (the grade is OK as per the Owners Manual)<br /><br />Questions #2: Any idea what this engine consumes for fuel on a GPH basis?<br /><br />

 

[TAL0362]

Re: Yamaha 9.9HP High Thrust Questions

Castrol 10W30 should be fine. Next to nothing on fuel consumption. My yamaha 4 stroke 15hp on my fuel flow meter is .1-.2 gal/hr at trolling speed(2-3mph), and .3-.4gal/hr wide open throttle(5-6mph) 21ft sea pro. These fuel flow #'s are supported by a 3 gallon external tank that can run the 15ph 4 stroke several days trolling.

 

[amsoilman]

Re: Yamaha 9.9HP High Thrust Questions

Originally posted by TAL0362:<br /> Castrol 10W30 should be fine. Next to nothing on fuel consumption. My yamaha 4 stroke 15hp on my fuel flow meter is .1-.2 gal/hr at trolling speed(2-3mph), and .3-.4gal/hr wide open throttle(5-6mph) 21ft sea pro. These fuel flow #'s are supported by a 3 gallon external tank that can run the 15ph 4 stroke several days trolling.

I would not use a gasolene engine oil in your Yamaha 9.9 outboard. It is best to use an oil that has been formulated for Water Cooled Marine Engines. IF you get an oil that has the latest ( NMMA ) National Marine Manufacturers Association ( FC-W ) Four Cycle Water rating, you would be better off. Oils with these ratings address rust protection as well as Viscosity stability.<br /><br />I use the Amsoil 4-Stroke Marine synthetic 10W-40 in my Yamaha High Thrust 9.9.<br /><br />My .02 worth

 

[gump218]

Re: Yamaha 9.9HP High Thrust Questions

I have a related question.... My 9.9 routinely has starting problems due to what I think is low voltage. Once I clean connections she kicks over fine.... Does a 9.9 4 stroke electric start provide any charging to the battery when running?<br /><br />Also, I get a good idle and seem to get good high speed but there is a point where the engine tries to stall out during acceleration. If I milk the throttle, I can get thru that zone to high speeed. Ideas?

 

[Kanadakid]

Re: Yamaha 9.9HP High Thrust Questions

Wayne,<br /><br />What is the additive and in what added quantities that FCW rated oils have that M1 or Castrol doesn't have ? No one has been able to offer this information. I hear the talk and the hype but don't see any new patents pending or information of what additional if any additives are in these oils.<br /><br />Dino oils offer no better proterction vs. Synthetics. <br /><br />But Synthetics do offer better engine protection and life vs. Dino.<br /><br />If anyone has the specifis info I would love to see it. Remember Yamaha and mercury has someone like Ashland / Shell make their oild for them.<br /><br />Kid

 

[ST]

Re: Yamaha 9.9HP High Thrust Questions

My official Yamaha owner's manual for my 1986 9.9 4 strokes recommends SAE 10W-30 or 10W-40 ("API, SE,SF,CC"); and that's what I am using....