Just purchased 1991 Johnson 175 hp low hour in excellant shape. Previous owner said to run premium gasoline but I find nothing in manual to that effect. What do you recommend and what is necessary.
Make sure owner didn't have high performance parts such as high compression pistons installed. This is pretty common in Texas, especially if he tournament fished. That may be why he specified premium.
Premium is a lower grade of gasoline than Regular. Premium simply has been refined more so that it takes a higher temp to ignite the fuel mixture.<br />The lower the octane, the less energy is needed to ignite the mixture.<br /><br />If the manual calls for regular, give it just that.<br />I know of no 1991 outboards that "required" premium.<br /><br />Dont listen to the commercials.. premium is not a better "grade" of gasoline, it just costs more to make. It's recommended in a lot of cars bacause they've raised the compression in the cylinders to the point that running regular causes pre-detination (pinging). In an attempt to squeeze the maximum amount of HP out of an engine, car makers are turning to this tactic. <br /><br />This is not the case with 2 stroke Outboard Engines.<br /><br />Nav
