Marked or regular fuel?

[ratherbefishing]

I had an interesting chat with a marine mechanin last week who suggested that the dye in marked gas was not good for outboards and recommended using 'regular' fuel. While I do like the fact that the marine marked is typically 89 octance, so by the time I see it is around 87 I am curious what others think. I understand the rationale to be that a little of the dye in the engine oil causes it to break down and lose it lubrication properties quicker. Given I've got a full tank of marked fuel at the moment I am not going to be draining it but what are others using/thoughts?
Cheers
RBF

 

[Whole in the Water]

I would want to get more confirmation and verifiable facts that the dye harmful before I would stop using it. Marked gas has been around a long time in both the agricultural and fishing industries and this is the first I have heard that it is harmful. I could be wrong though.

Long live wild salmon!!!

 

[Island Fish Lifter]

87 is too low for any marine application. Most times a person cant hear the pinging noise so you wont know its happening until you hear the dreaded knock- knock.
The die in the marine gas can be harmful in a number of ways.. one is that it can plug injectors. (Its actually not that common).
Soo what to do.. I run marine (dyed) gas and personally have never had a problem. I have however lost a cylinder in a 470 mercruiser because of using 87 octane fuel... it was my dads boat.[xx(]

Fill the dam tub!

 

[ratherbefishing]

I've been running dyed gas without a problem but I use the gas fairly quickly. I am wondering if mid-grade regular would be a better option for the winter when the boat doesn't get used as much.

"87 is too low for any marine application" - how do you figure? With todays modern EFI engines, they are mapped for specifc octane ratings are they not. Burning Supreme in an engine rated for 87 octane would be wasting money would it not? That said, I do not believe 87 octane is 87 octane most of the time as the octane rating degrades quickly (which is why I like the mid-grade). Also, I am pretty sure most engines now run with some for of knock sensor (I know my sleds sure did).

 

[profisher]

I've run marked 89 octane exclusively for over 25 years and never had an issue because of it. I use the fuel quickly in the summer and add Stabil for the winter months when it sits in the tank and engines. I think using a good quality oil, keeping water out of the fuel system, proper filters and good maintenance practices are more important for long engine life than worrying about fuel dyes.

 

[Island Fish Lifter]

A knock sensor will retard timing upon sensing detonation. That said, it reduces efficiency therefore reduces fuel economy.
What I dont know is by how much.

Fill the dam tub!

 

[Gunsmith]

A lot depends on the motor, some more and others less. You can count on a difference as Island Fish Lifter states.
For many reasons identical motors perform differently and if you monitor your gas consumption and try diferent octanes and makes of gas you can get more out of your motor.

 

[redliner]

I had the same concerns over oil break down. I would have to think any contamination of your oil will shorten it's life. Although in a some locations marked marine is your only choice. If I have the option I run reg. midgrade.

 

[Gunsmith]

On that line of thought we do not know what the dye is made from.

 

[Island Fish Lifter]

I know the die is extremely toxic and usually is not measured accurately.

Fill the dam tub!

 

[speydog]

Never heard any evidence that dye affects any motor.
Have found that the extra couple cents per litre for mid grade over reg is worth it. Just seems to run smoother. Especially on older motors.

 

[Island Fish Lifter]

most marine gas is midgrade 89.

Fill the dam tub!