Required Octane

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01-19-2003, 06:51 PM

First Mate

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Required Octane

I know 502 ,mags can use regular fuel, what do HP500's and 575's require

01-19-2003, 08:14 PM

Vinny P

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HP 500 's run on regular as well. According to Mercury Marines website, the 575 sc requires 92 octane fuel.

01-20-2003, 12:40 PM

Von Bongo

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I see 92 said a lot on the 575 but on page 32 of my operating maual it says:

Unleaded premium 91 (R+M)/2 or 96 RON

I still run 92 but if Merc says 91 is OK I would believe that it is.

01-20-2003, 01:39 PM

Shooter

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Same question on my mind. Does running 89 octane over 87 on stock 502 mags more a mental thing - does it really matter on a stock motor?

01-20-2003, 02:46 PM

Von Bongo

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Quote:

Originally posted by Shooter
Same question on my mind. Does running 89 octane over 87 on stock 502 mags more a mental thing - does it really matter on a stock motor?

89 is a waste of money and also helps make your transom black in a stock 454EFI, 502EFI & 500 EFI motors