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Mercury Outboard Oil Mix Ratio?

Old 08-10-2002, 07:18 PM
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Default Mercury Outboard Oil Mix Ratio?

This is a question for the Outboard Guys.
My Friend has a pair of 99 280 Hp. Mercs, He is running Klotz synthetic oil at a 32 to 1 ratio . I think this mixture is excessive for a synthetic oil.I used to run 80 to 1 in snowmobiles. What oil and ratios do you in your Mercury outboards?

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Old 08-11-2002, 01:26 AM
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I ran 50:1 in all my pleasure motors. I ran 32:1 in all my dragrace motors.

Whatever ratio his Merc manuals specify should be fine with a premium oil. Be sure to note that changing ratios changes carburetor jetting.
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Old 08-11-2002, 03:03 AM
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at 280 I assume these are 2.5 efi's. I would not thin them out at all. Better to run them with plenty of oil then not enough. Cheap insurance if you ask me

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Old 08-11-2002, 08:43 PM
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More oil is not always better!! Oil mixed with gas and then burned is the final fuel. On a 2/cyl., oil passes through the crankcase with gas and maintains a healthy lower end. The least amount of oil needed to lubricate the crankcase is what you want. More oil than needed lowers the octane of the fuel you burn leading to detonation. I have always found that a really good synthetic (I use AMSOIL mixed at 75 to 100/1) will give you max. performance at even over recommended RPM's, burn clean, and keep the engine very healthy. --- Jer
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