auto blend 100:1

[bos22]

I purchased a boat with an '87 30 hp Evinrude and noticed the mix ratio was 100:1. I thought that was too lean based on my prior experience and asked my local marina mechanic. He said that I should ditch the autoblend tank altogether and simply run 50:1 premix. Is this the best idea? and can I simply use the autoblend tank without oil in the oil tank and premix at 50:1 and leave it at that?

 

[rolmops]

Re: auto blend 100:1

Hello.<br />Your mechanic is advising you to do the right thing. 1:50 is double the amount of oil and thereby double the amount of lubrication,quite possibly doubling the lifetime of your engine.

 

[BillP]

Re: auto blend 100:1

Hey bos22,<br />The motor doesn't need more than 100:1 for lubrication. There is a giant safety factor in the factory oil numbers. It seems to me they published 1986 100:1 motors would be ok at 150:1 at worst case and 300:1 at low speed. It won't hurt to run 50:1 but the motor will run dirtier and need decarbing more often to keep crud from building up.<br /><br />The reason OMC stopped doing 100:1 was because it left too little film on the parts for long term storage. Motors were coming back under warranty for corrosion issues so they changed back to 50:1. I got that info from a friend who at the time was the warranty manager of OMC International for S.America, Bahamas and Bermuda. He told me not to worry about it if I didn't let the engine sit for months between use without fogging. He also endorsed removal and elimination of the VRO and Accumix systems.