Which Octane To Use?

[TRONMAN2000]

I have a 2000 Glastron GX 205 with a Volvo Penta 5.0 GL in it. My manual doesn't specify an octane for the fuel. I was just curious as to which octane is best for this engine? I have used both 87 and 93 (at different fill ups) It seems to do fine with either one. I just don't want to hurt my engine! (not that anyone does) These forums have been very helpful to me since I bought my boat last year. i've been able to do basic repairs myself. Thanks for all your help!

 

[MRJ82]

Re: Which Octane To Use?

Which one will make make you feel better about yourself, 87 or 93??? If it runs on 87 without hearing spark knock, you will be good to go. But you already knew that didn't you???

 

[TRONMAN2000]

Re: Which Octane To Use?

Don't have any knocking, but it seemed like it was easier to start when hot with the 93 octane. Sometimes it would take some extra starter cranking time to start with the 87 octane. Don't know if it was the octane or something else? It starts right up without pumping throttle when cold.

 

[QC]

Re: Which Octane To Use?

The only time I consider anything other than 87 is very high ambient temperatures (above 105). Even that is probably a waste of money.

 

[BF]

Re: Which Octane To Use?

It varies by location... but up here, 87 and 89 octane are ethanol blends... "premium" here is still ethanol free. That's why I use it, not really b/c of the octane rating.

 

[lowkee]

Re: Which Octane To Use?

I get my fuel piped in from NASA. The only spark knock I hear is the launch ramp disintegrating behind me when I fire it up!

3...
2...
1...

Seriously, though, I've not heard of a 5.0L requiring high test, even in a sports car.

 

[AZChapBoat]

Re: Which Octane To Use?

My boat is a '98 and has a Volvo Penta 5.0GL and my manual says to run 93 octane. Marina only carries 91 octane fuel so I don't have much choice. I've also read that ethanol in boats is not so great, but can't remember the specifics.

 

[HT32BSX115]

Re: Which Octane To Use?

I have a 2000 Glastron GX 205 with a Volvo Penta 5.0 GL in it. My manual doesn't specify an octane for the fuel. I was just curious as to which octane is best for this engine? I have used both 87 and 93 (at different fill ups) It seems to do fine with either one. I just don't want to hurt my engine! (not that anyone does) These forums have been very helpful to me since I bought my boat last year. i've been able to do basic repairs myself. Thanks for all your help!

Volvo evidently has fuel recommendations in their owners manuals like everyone else.

Go to http://www.volvo.com/volvopenta/na/...ice/publication_search/publication_search.htm for instructions on how to get a manual.

For Mercury,

Go to http://www.mercurymarine.com/serviceandwarranty/mercruiserfaqs/fueloil.php


Cheers,

Rick

 

[QC]

Re: Which Octane To Use?

You can get the Owner's manual free online at Volvo. I have a copy if you can't find it, just PM me your email addy. It's a 2005 dated manual, but it shows 5.0 GL on the cover. It says 89 in the US and 93 RON, so that means 89 . . . It also says that anything less than 87 is bad, and then even goes on about ethanol. Tool long to type and I can't C & P from it . . .