Use a good grade of Non-Alcohol unleaded fuel if you can get it. Mid-grade would be a better choice for your motor, considering the HP level. Mercury doesn't recommend using Premium if it's Gasohol.
Mixture for this motor is 50:1 unless you have an external auto-injection fuel tank and you'd probably notice that by now!
Use mfr’s oil or a good aftermarket such as Penzoil Synthetic Blend (priced cheap at Wal-Mart).
Use a carbon-cleaning fuel additive such as Seafoam, Chevron Techron, Berryman’s B-12, OMC Carbon Guard, Yamaha Ring-Free, etc. It'll keep the rings from sticking and they'll like that!
Seafoam is probably the best and you should be able to find it in at least some of your local auto parts stores.
www.seafoamsales.com
Replace the impeller unless you know the P.O. had done it recently. Will save you thousands $$ in preventing a powerhead meltdown from a $25 part.
Do the link-n-synch outlined in the link below, to keep the motor running smoothly and ensure you don't have too much spark advance (which will burn up the pistons):
Short version:
http://forums.iboats.com/showthread.php?t=168855
Long version:
http://forums.iboats.com/showthread.php?t=128495
Make sure your motor is turning approx 5500 rpm Wide Open Throttle (WOT) with a light load (driver only). Inlines don't like to be over-propped. If you're not achieving somewhere close to that, recommend you get a prop with less pitch, which will allow the engine to 'spin up' into its power band.
Anyway, there's a short "Care and Feeding of Inline Six" lesson. The Inlines are great Classic outboards and when given the proper care will last you many seasons.
HTH & welcome to iBoats..............ed
1982-1988 mariner 140 hp fuel/oil mixture?
Linear Mode
