4 stroke engine oil

[BAIT956]

I have a 2001 Yamaha 80 hp 4 stoke. Always have used Yamalube 4 stroke oil as the owners manual recommends.

What is the difference between 4 stroke oil and regular 10-30 or 10-40?

Can I use the regular stuff safely? It is less expensive.

[DinkADunk]

Different additive package. Same applies to motorcycle oils (vs auto oil). Auto oils aren't normally NMMA FC-W certified, which your 4 stroke marine oil probably is.

[theoilman]

FC-W 4-stroke marine motor oils are very different from automotive oils - very different additives. Marine engines run much cooler, rev up to much higher rpms and rev up extremely fast. Marine engine oils will have much better anti-foaming additives, better extreme wear additives, better corrosion inhibiters, etc.

I believe most marine 4-stroke oils are synthetic or synthetic blends.

AMSOIL does have the FC-W in 10W-30 and 10W-40.