Does running the VRO cause lower carbon buildup than mix?

Mark42

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Oct 8, 2003
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I am wondering if the variable mixing feature of the VRO causes a cleaner engine because it is tailoring the oil ratio to the load. <br /><br />I put myself through college by working as a small engine mechanic and saw the damage that carbon buildup did to small 2 cycle engines that ran straight mix and never got maintenance until they stopped working. Yikes! That carbon in the exhaust ports chewed up the rings and pistons bad. Just like sandpaper. I want to prevent that condition from happening in my Evinrude, and wonder if the VRO will help keep it cleaner than straight mix.<br /><br />I run the high octane fuels to get the benefits of the cleaners that they contain. Hopefully this will pay off in the long run.<br /><br />Thanks,<br /><br />Mark.
 

seahorse5

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Jan 24, 2002
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Re: Does running the VRO cause lower carbon buildup than mix?

Read the FAQ section about the VRO and how it works.<br /><br />Besides the oil and gas forming carbon, make sure the thermostats are allowing the motor to come up to a proper temperature to promote cleaner combustion, thus minimizing carbon buildup.
 

Dhadley

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Feb 4, 2001
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Re: Does running the VRO cause lower carbon buildup than mix?

Ditto.<br /><br />And make sure the motor is set up so its not lugging. If it were mine I'd use the recommended fuel too.
 

Mark42

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Re: Does running the VRO cause lower carbon buildup than mix?

The owners manual indicats that 87 octane is the mininum requirement, but strongly recommends that the higher octane fuels be used specifically for the benefits of the fuel additives they conain. <br /><br />Assuming that I have the boat propped right and thermostats are working, will the 93 and later VRO result in a cleaner engine than straight mix? or is this an unknown?
 

phatmanmike

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Oct 24, 2003
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Re: Does running the VRO cause lower carbon buildup than mix?

dont forget about regular decarbs...either by using the spray in the carbs method, or by mixing with the fuel
 

Dhadley

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Re: Does running the VRO cause lower carbon buildup than mix?

The last year for a VRO was 1992. In 93 OMC went to a straight oil injection pump. It does vary somewhat but not as great as the variable system. <br /><br />The set up on the motor seems to have more to do with coking than the actual ratio. We see high performance motors running double oil (24:1) that never coke up the rings. <br /><br />As seahorse mentioned we look for proper engine temps and combustion temps. You don't want the motor too cold nor the combustion temps too high. Proper capable rpm, cooling system operation, correct spark plugs and proper fuel all factor in. Obviously the quality of oil has a lot to do with it too.<br /><br />With todays fuel all grades have the same ammount of cleaners. There was a time when this was not so. The higher the grade, the more cleaners. We try to stay away from excess octane as this causes higher combustion temps (with todays fuel) with stock compression.
 

rickdb1boat

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Jan 23, 2002
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11,195
Re: Does running the VRO cause lower carbon buildup than mix?

The way I feel about it is. If you are running the proper RPM's, 87 octane fuel and don't troll alot, the system should stay pretty clean. I never did a decarb. in all the past years I've been running my motors and they all looked very good inside. On that note, with all the talk about it, I now decarb once a year just for the heck of it. I really don't get all that much out of it, but it can't hurt.... I believe that keeping you motor in proper tune and running it at peak effiency will certainly cut down on carbon build-up...
 
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