FUEL WITH SYNTHETIC OIL ADVICE PLEASE

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FUEL WITH SYNTHETIC OIL ADVICE PLEASE

Postby boz » Fri May 21, 2010 4:07 am

I have several vintage 4-stroke engines like the Kalt FC1, OSFS 60, British Magnum etc. which I want to run up on a test bench. I note that most of the manufacturers manuals recommend fuel with a castor content but as I have access to some high tech fuel with a synthetic oil ( free of charge ) I would like to know if there is any good reason why I shouldn't run these engines on this fuel. I know I should do what the manufacturers recommend but since the manuals were written synthetic oils in fuel have come a long way. What do you experienced engine guys think ? Should I chance a fuel with a 20% synthetic oil content. I'm no expert but I cant think why it should do any damage.
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Postby Frank Klenk » Fri May 21, 2010 7:17 pm

Hi Boz

I would not hesitate to run your 4 strokes on synthetic oil based fuel. The key I think to longevity is after the engine is shut down. You need to get after run oil in there to eliminate the effects of nitro's mositure absorbing quality. I have run several 4 strokes on Cool Power for years with no issues. Speaking of Kalt 4 strokes, would you be interested in selling one?

Frank 8)
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Postby boz » Sat May 22, 2010 4:49 am

Hi Frank, thanks for your reply. I will go ahead and run these engines with the synthetic oil based fuel unless I hear from someone else who gives me a good reason why I shouldn't. The Kalt engines I would like to keep as I intend to run one and display the other. If I change my mind about selling one I will let you know.
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Postby chiefss » Sun May 23, 2010 2:15 pm

There is no problem with straight synthetic oil as long as you make sure you get all the blow by residue out of the crankcase when done running. I squirt WD-40 into the breather until it comes out the front bearing. Then a good slug of after run oil (your choice) in the the breather.

I do use nothing but castor oil in my engines but then I always have and my bearings last forever and I don't worry about after run oil.

I use 20% oil but 18% is OK.
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Postby boz » Sun May 23, 2010 6:01 pm

The fuel I intend using is 5% nitro with 29% synthetic oil.
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Postby Frank Klenk » Sun May 23, 2010 6:53 pm

Boz

That is more than enough oil and the nitro % is low. Use a bit of after run oil and you won't have any problems.

Frank
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syn fuel

Postby collie » Sun May 23, 2010 7:23 pm

as long as you use the correct amount of oil you should be all right,just dont run the motor LEAN.the only other thing to consider is the metalurgy of your engines was design to use the oils of the day ,namely Castor.where as modern motors were designed to run on modern oils.Syn.
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Postby chiefss » Mon May 24, 2010 12:11 am

29% oil is way too much, 20% is more than ample. With 29% oil you will find four cycles tend to backfire and throw the prop which can be very exciting. 10% nitro makes a four cycle idle better but 5 % is OK. 5 to 15% nitro is good for most 4 strokes. The YS's like 20% and really drink it down. I use 20% Castor oil and 10% nitro in all my glow engines except my tartan twin which uses straight methanol and 8% castor.
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Postby boz » Mon May 24, 2010 5:17 am

The 29% is a typo ! Will be using 20%. Thanks for all the replies, great help.
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