Changing oil in four-stroke

[Luck e 1]

Got a two year old Yamaha 25 horse, 4-stroke. We want to change the oil and oil filter.

Can you use regular 5w30 or 10w30 oil, or do you have to use the Yamalube?

[fish2live]

i was told by a marine mechanic that a 4 stroke engine is a 4 stroke engine you do not need to use special oil just regular car oil is fine i would suggest running synthetic. i use car quest synthetic because at 4.00 a quart you can't beat the price.

[18 inch Crappie]

Use only marine oil, they have additives that adsorb water and others made just for a boat oil. It is true a 4 stroke is a 4 stroke but one you run on dry pavement and one on run on water. If you want to save $5 and then do $1000 worth of damage to your motor then it was worth the $5 savings.

[Random guy]

Be careful, marine grade oils have higher shears and tighter viscosity standards due to the constant high revving conditions of a outboard motor. How often does you car run at 5-6,000 RPMs and how often or should I say constantly does your outboard run at 5-6,000 RPMs. Not to mention you are dealing with huge amounts of moisture that marine grade have inhibitors within them to help with the corrosion and milking issues.

You can use auto grade oils that will work, but do you want to be so mean to the one thing that takes you fishing?

[Scott K]

Dumb question, I dont use it but does amsoil have these additives in it for water?

[Luck e 1]

Thanks guys...I will probably just use the Yamalube becuase I really only change it once a year...so the savings wouldn't be that great compared to the potential risks.

[theoilman]

Yes, AMSOIL does have the oil for marine 4-stroke engines.

Especially when new, you should use a "NMMA" certified oil - and the specs really are different - these engines turn up higher RPMs and do it quicker than automotive engines. Plus you need NMMA certification to meet warranty specs for the marine 4-strokes.

AMSOIL has NMMA certified marine 4-stroke oil in 10W-30 and 10W-40. E-mail me off the forum for more info.