Congrats on your purchase. A
As the outboard is used andyou don't know how it has been maintained - I would replace the thermostat. Then pull the lower gearcase and check the water pump impeller, housingand plate. If the impeller, housing and plate all look good, (no scuffs, nicks,grooves or signs of wear in anything) I'd still replace the impeller. I'dreplace the fuel filter. I'd change the engine oil... For engine oil I runMobile 1 Full Synthetic (available at Walmart in a 5 QT jug) in either 10W30 or10W40. If always running in warmer weather and water go with 10W40, otherwise,go with 10W30. I see no need to waste $ on Yamaha's "Yamalube" engineoil or Yamaha's "Ring Free" additive. If the spark plugs look goodthere's no need to change them unless you want to... If it's running smooth, noneed to change in my opinion. I'd change the lower unit gear lube. OB gearcase lubeis pretty much all the same so any marine outboard gearcase lube will be justfine. Check the sacrificial Zincs on the engine... If they are chalky-white clean all thechalky white off of them with a stiff wire brush until you are back down to grey Zinc.When you gas it up for the 1st few times, run Seafoam fuel treatment &fuel system cleaner (available at any autopart store) at the recommended ordouble dosage for a few tank fulls and then run Marine Sta-Bil (the greenvariety) fuel additive ALL THE TIME EVERY TIME YOU FILL THE TANK as I do. If atall possible and if it is available close by, only run 100% gasoline and steerclear of 10% ethanol blended gas that is sold at 99% of auto gas stations. Askaround and see if there is a station or marina close to you that sells 100%gas. It costs a bit more but after being inside and out of my engine severaltimes dealing with ethanol created gumming, clogs, etc. I'll never run ethanolblended fuel again if 100% gasd is available as I'd rather be having fun than
wrenching on my engine. Thermostats, lubricants, fuel filters, water pumpimpellers, fuel additives and 100% gasoline are all cheap... A new outboard i***PENSIVE. Flush the engine with fresh water and hose down the exterior afterevery use if you run it in salt water. When running try to run at a reasonableRPM 4000-4500 most of the time when cruising (not full throttle like we all didwith the 2-strokes that can run all day at WOT and think nothing of it). Onevery trip, do feel free to run WOT for 5 Min or so generate some heat, helpburn away carbon deposits, and keep the rings from "seating in" to aset RPM operating range. Properly maintained and not abused, a 4-stroke Yamahawill run for 1000's of hours.
If you go to Simyamaha's you can bring up schematics on your specific engine and order all necessary parts which is where I order my parts from.
