Between the ice auger, boat, weed whipper, edger-I've forgotten what gets what- I need to know the fuel to oil ratio for a 20 year old Mercury 20HP outboard. Thought it was 50:1, but cheaper to ask now than ruin the motor.

Thanks-

20 years ain't that long ago. I'd run 32:1 and check the plugs after a tankfull. Most everything else these days comes out of my 50:1 can.

Newcastle, had my oil tank taken off a 94-25hp johnson dealer told me to add 16oz of oil to a 6gal tank . aurger,chainsaw,& other small engins 40:1 is the norm

Petroleum oils - almost all pre-mix outboards back to 1970 (probably earlier) was 50-1. If you choose to use AMSOIL Saber Outboard Synthetic you can use it as lean as 100-1. If you choose to use AMSOIL HP Injector in a pre-mix outboard use it at 50-1.

I would also suggest amsoil sabre outboard. I started using it last year in my 15 HP mariner @ 100 to 1 and the smoke is gone! Runs like a top too.

I have an early 80's evinrude that runs awesome always has, but it does smoke quite a bit. I mix it 50-1, I wonder if the amsoil sabre outboard would do me any good and if I would hurt anything mixing it any leaner with the amsoil.

You can safely use the AMSOIL Saber Outboard at the lean 100-1 mix ratio in a stock pre-mix outboard and AMSOIL gives you the lubricant guarantee at the 100-1. But if you choose to run it richer, just being unconfortable that lean, start richer. Even at 50-1 it should be nearly smokeless. Then adjust to leaner in steps as you feel confortable with it.
Or, if you want to stick strictly to the 50-1 ratio, use the HP Injector as a premix at 50-1.
AMSOIL's di-esther based synthetic two-cycle oils burn away clean leaving no carbon, ash or other residue behind.

Another vote for Sabre oil. One cannot beat it in all of ones small engines.

Not sure about Merc but my '88 Johnson 25 had a sticker on it that said 100:1. It also had an 'Accumix' tank built in the main tank. The mechanic told me to rip the 100:1 sticker off and run 50:1. I tried the 100:1 ratio with synthetic pre-mix and didn't notice a difference. Don't feel it's worth the risk. If you've ever taken apart a 2 stroke engine, you know how tender the bearings are. The extra ounce of oil doesn't hurt anything.

My weedeater, chainsaw, and auger, all run on 32:1.

HUGE TIP: Look for the non-oxygenated fuel!!!!

My two cents.

TC