GC in Outboard Motor

Joined
Feb 19, 2003
Messages
230
Location
SLO County, CA
Wed I bought a nearly brand new boat package that included a Tohatsu 6hp 4-stroke outboard motor...boat and motor first sold in Sep'05. The motor has ~8 hours on it. Manufacture oil recommendations are SAE 10w30/40 thru 20w50. Break-in period is 10 hours but I going to change the oil now. Think GC would be a good canidate? TIA...bgin
 
Joined
Apr 13, 2005
Messages
234
Location
Scotts Valley, Ca.
'00obw, being the cautious type, in your situation I would change it out for Havoline, Chevron... 10-W30 for four or five more hours just to be sure of the brak-in. Then I would go to the GC. I might even add a touch of LC-20 to the GC just for grins. John
 

'00obw

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Joined
Feb 19, 2003
Messages
230
Location
SLO County, CA
quote:
Originally posted by John Hilmer: '00obw, being the cautious type, in your situation I would change it out for Havoline, Chevron... 10-W30 for four or five more hours just to be sure of the brak-in. Then I would go to the GC. I might even add a touch of LC-20 to the GC just for grins. John
Well I changed the oil with TropArtic 10w30 synblend with a 1/2oz of LC and run this for 10 hours or so. I thinking to use GC after about 40-50 hours.
 
Joined
Mar 21, 2006
Messages
461
Location
Fredericksburg, VA
They formulate oils just for the 4-stroke outboards. They differ from car oils because of the unique operating conditions. You might look into the Mercury or other outboard manufacturer's oil, or the Amsoil. The GC might be OK, but what if the anti-wear add pack was for the wrong temperature range? The outboard oils are also formulated for corrosion protection.
 
Joined
May 17, 2006
Messages
4,381
Location
Central Wisconsin
Most outboards run at 140-160º. A heavier oil isn't needed. While ordinary auto oil is fine in these engines, keeping an eye in it condition is a wise practice. The manufacurer would REALLY like you to buy their expensive, made especially for you, oil, it's rarely necessary. Same situation with motorcycles and their 'special purpose' oil.
 
Joined
Mar 2, 2006
Messages
1,527
Location
Mid-West, USA
I have a 4.3 Litre Mercury/Mercruiser I/O engine in my boat. It is a couple of years old now, and has had two oil changes with Mercuy oil. It had the third and last with Amsoil, and has ran fine, maybe even smoother with the Amsoil, but I have nothing to substantiate that with. I also have new SS prop, which definately has made it smoother, and much faster. I know that this is not an O/B motor, but, not much boat talk on here, so, that is my $0.02. Also, temp wise, my boat runs at about 175 F, and my car runs at about 180 F, so temps are about the same for me.
 
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