Guest paul Report post Posted March 31, 2011 I recently purchased a 2006 lund fisherman with a same year 90 optimax on it. What grade fuel is required for this motor. Tank is over 3/4 right now i will drain and put in the truck, i purchased in the states and am worried bout ethenol. Dont know if stabil was introduced for storage or not. Quote Share this post Link to post Share on other sites
Guest fishfinn Report post Posted March 31, 2011 Found this on BBC for a Mercury Opti, but I can't vouch for the accuracy...maybe others can comment? This is a commonly asked question. Here's the problem: Higher octane fuels burn SLOWER and COOLER (meaning in your case, an incomplete burn, and DECREASED performance). Due to the incomplete burn, carbon levels WILL increase. Although you MIGHT be able to run the engine on this fuel utilizing APPROPRIATE fuel treatments (INCLUDING QUICKLEEN), carbon buildup is inevitable. Over time, carbon can build up on the piston crowns, creating "hot spots" (literally small glowing embers of carbon that act as minature "glow plugs"), causing a potential for pre-ignition of fuel and detonation (resulting in severe engine failure). This usually won't occur in a short time period, but over time, the potential is there. IMHO.... 87 or perhaps 89 octane (with no more than 10% ethanol content) is more suitable (and may well be all you can find when you're out on the road). Quote Share this post Link to post Share on other sites
Guest crashj Report post Posted April 17, 2011 I've run 87 octane with 4oz quick kleen per 10 gal and 2 oz of seafoam per 6 gal gas in my 99 200 opti and shes still going strong Quote Share this post Link to post Share on other sites