Thanks guys...there are alot of choices out there and I think I am going to move up to probably the Amsoil or the Mobil 1 V Twin. The 30 wt seems to really thin out after a good run around 4,000 rpms. Dont have a oil temp gauge but I probably should invest in one.

You want more Zinc in your oil Syn or mineral? This company sells it. But not for use with a catalytic converters. http://www.cam-shield.com/index.html Doug

You should install an oil temp gauge, and stop with the 30 wt. oil LOL

An oil temp gauge should be used regardless of what grade of oil you use.

All oil thins with heat, when you start with a realitivly thin oil like a 30weight of course it will get very thin when hot, the hotter it gets, the thinner it becomes until the oil's viscosity is so thin it cannot support the load of the crank and you wipe out your bearings.

When you start with a heavier oil (20w50), it can tolerate the higher temps with out a catastrophic loss flim strength.

Ken

Two biggies to pay attention to in a marine engine is oil pressure and oil temperature. Get the gages and pay attention. They will tell you what kind of oil you need for the type of driving you do. The harder you run and the more HP you run the hotter things get and the better oil you need so that the oil will survive and adequate pressure will be maintained. A general rule of thumb is 10 psi oil pressure per 1000 rpm and from the engine/crankcase 220f max oil temperature best and 260f-280f slow down and cool down. Bigger oil coolers, oil lines/fittings and such can help.

This is what I run and so far I'm really happy with it.

http://www.amsoil.com/storefront/wcf.aspx

Rage, don't worry at oil temps over 220F worry at oill temps of 280F.

Modern day products can tolerate high temps, espically synthetics.

If you bounce off 300F often get larger coolers. 220F is ok.

Ken

Ken, what's your thoughts on these two oils for this application.


I've been running Mobil 1 15-50 for several years in my old flat tappet Pachanga with zero issues.

Local marina says to run Merc 25-40 petroleum as he says the Merc oil has more zinc than the Mobil 1.

What's the real story on zinc levels of these two popular oils?

Thanks,

Kurt

Somebody sent this to me..alot to learn.http://www.offshoreonly.com/forums/g...brication.html

Kurt, I will swing by the local marina and buy a quart of Mercury 25w40 and send it out for elemental analysis.

Could be a couple/three weeks though.

Ken