E10 Is No Good But What About Higher Octanes?

[barker]

hello all,

having looked through the posts and read the advice against using E10 unleaded, i was wondering if the higher octane rated unleaded fuels are recomended? a few of my local servo's are only stocking the E10 and not the regular anymore, so what to do?

i run a 1999 model yamaha 85hp cv 2 stroke.

ps. by consensus the xd-50 oil sounds like the recomended premixer for good performance and lower emissions, any opinions or alternatives?

thanks for any help. barker.

[a boat]

Hi Barker, premium unleaded or a fuel with a higher octane rating will burn easier and in theory give you better performance and fuel economy. I have used both premium and regular unleaded in my 225HO Evinrude and to be honest did not notice any difference.

If you can only get the premium unleaded you are not hurting your engine at all, only your hip pocket.

I stock XD-50, but honestly being a semi-synthetic oil I think for a pre-mixer it is about as good as you can get and worth the little more it might cost over a generic oil in my opinion.

Cheers,

Huey.

[pelican]

Some higher octane fuel has a reputation as not having a long storage ability, holding it's octane ( compounded with a non sealed boat tank) and there is some slight issues with fuel mixing between companies brands now and again. Different fuel companies are creating the extra octane in different ways and a couple of the components they use may have issues with premix oils and water / cndensation. The motorcross motorbike sites have noted some failures due to poor oil mixing with premium over the years with some bikes also having issues with gaskets , deposits, and seals like what happens with ethanol fuel but to a lesser degree. I have avoided it on the above basis and until a outboard company says their computer can actual take full advantage of it rather than just say some extra power comes from it I'll use normal unleaded especially in 2 strokes.

Double check the oil company website and marine manufacturers websites as there is notes in their question sections or send them an email for an update from there point of view in regard to storage , oil mixing and marine use for an current fuel products. I'd also be interested in the response.

Like with all these style of things the theory is great but marine applications, the non sealed marine tanks and poor fuel storage conditions on boats are rarely considered. So it in it's purest form in perfect conditions can do no harm in modern motors hence the manufactures say it is allowable but you must consider if your fuel system is up to standard and you use your fuel regularly enough.

Pel

PS Car technology with different exhaust sensors can actually tell a bit more about fuel and the way it is burnt than most boat motors so not sure if knocking , detonation could be a issue. Different on every motor with different parameters in computers and different sensors.

[pjbink]

I found this post elsewhere which suggests its not a good idea to use premium in boats:

Re: Filling up fuel tank to full after use?

There is an excellent article in the latest Australian Fisherman and Boatowners (F& magazine. Well worth a read.

Too much detail to go into fully but the Senior Fuel Chemist at BP states "High octane (95 & 98) fuels should NOT be used in outboard tanks. Only normal unleaded should be used"

He recommends keeping boat tanks one third full to stop condensation and add at least one third of fresh fuel before going boating. Do NOT use fuel with Ethanol added. "Normal life of fuel in a boat tank is about 3 weeks (much less in high temperatures) after which the fuel starts to get too heavy for the fuel system". (the "heavy" part is explained in the article).

Edited May 17, 2008 by billfisher

[ETTY]

Premium fuel would be a better option in any engine as it has more energy per unit, retards pre ignition and usually is cleaner burning.

People must remember an outboard/inboard is just like any other engine and something that will improve a cars performance will increase a boats performance. The Honda range (90hp ish) is the same engine used in the Honda Jazz!

So with premium you will get cleaner and more complete combustion, better performance and more km's per litre and it has a higher energy rating per litre than standard unleaded. All these factors are the same when you put it in your car.

If you got the money for sure use it but unless it's especially needed it's fine to use regular. Maybe a hit of premium now and then when going on a long trip or when operating constantly at high revs (skiing etc) will do the engine good. Many people do this when going on long highway trips operating at high speeds.

Also all fuels can be mixed together as they generally all come from the same place. At the moment especially, the Shell catalytic cracking unit is not functional and is using fuel from the other providers as a substitute. Brands need to be able to "mix" as in fuel shortage situations Shell can give fuel to Caltex or whatever.

[domza]

I have run shell optimax 98 fuel in my 85hp merc ever since i got it with out any problems.

[barker]

thank you all for your interesting and informative replies.

seems as though the E10 is definitely a no go, higher octanes are usable and a semi-synthetic premix oil would be the best bet for cleaner running/protection/etc.

next decision is whether to drive around using petrol - to find regular unleaded petrol - to save on filling the boat with high octane unleaded petrol that gives no noticeable performance gains.

regards, barker.