Syntheic 2-stroke oil vs conventional Any difference?

drchpete

Seaman Apprentice
Joined
Jun 21, 2009
Messages
37
Is there any reason I should not use synthetic 2-stroke oil in my 2000 Yamaha 40, or my 2003 Yami 9.9? I've always used conventional but was given a brand new quart of synthetic. What about mixing conventional with synthetic?
 

robert graham

Admiral
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Apr 16, 2009
Messages
6,908
Endlessly debatable subject, but that said, I've used the Pennzoil 100% Synthetic oil in my C90 Yamaha for many years and I feel it smokes less and may offer some benefit regarding less carbon on plugs and pistons....
 

Chris1956

Supreme Mariner
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Mar 25, 2004
Messages
27,816
1) Most 2 cycle OBs call for TCW-III certified oil. Unless your motor calls for a synthetic TCW-III, you can safely use either conventional or synthetic 2 cycle oil.

2) Some say the synthetic-blend 2 cycle oil smokes less. However, I have found that the amount of smoke produced by a particular oil to be difficult to quantify.

3) Usually dino oil is cheaper than synthetic or a blend. What does your wallet say?

4) Normally synthetic oil will mix fine with conventional oil.
 

WIMUSKY

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Sep 26, 2009
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I'd run the conventional oil down as much as possible, then add the synthetic...
 

GA_Boater

Honorary Moderator Emeritus
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May 24, 2011
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Dino and syn mix with no problems. Use your free quart of syn as long as it matches the requirements of your Yammis.
 

dingbat

Supreme Mariner
Joined
Nov 20, 2001
Messages
16,038
I've run Dino, Semi- synthetic and full synthetics oils.

Your not getting Dino oil anywhere near my boat. The stuff works almost as well as ipecac. Keeps Champion spark plugs and Carbon Guard in business

I like full synthetic performance, but I don't like pouring $150 worth of oil in the tank every fill up.

Semi-synthetic is a great compromise between performance and cost. I run XD-50 at $22 a gallon, $66 a tank, at case lot price.
 

Sea Rider

Supreme Mariner
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Sep 20, 2008
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12,345
I'd run the conventional oil down as much as possible, then add the synthetic...

Some OB brands manuals states not to mix 2 different TCW-3 2 strokes oil one on top of the other when switching to other brands oil, could experiment gelling issues which gives poor lubrication. Ideal is to burn most of the current fuel leftovers as previously mixed before mixing a different oil brand.

Happy Boating
 

dingbat

Supreme Mariner
Joined
Nov 20, 2001
Messages
16,038
Some OB brands manuals states not to mix 2 different TCW-3 2 strokes oil one on top of the other when switching to other brands oil,
Part of tcw testing involves product mixing. No mix = no tcw certification
 

Sea Rider

Supreme Mariner
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Sep 20, 2008
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12,345
Part of tcw testing involves product mixing. No mix = no tcw certification


Spot on answer, you always learn something new from others, was in boubt myself as sometimes don't go per manuals. Thanks.

Happy Boating
 
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