gas to oil ratio? 78 murc 500

[crappyfisherman]

any one know what ratio i should be using with my mid 70's "500 Mercury"? ive been told 50-1 but would like to know forsure, keep the old girl happy.

 

thanks

[GBW]

I too run 50:1 in my 70's Jhonson unit. (easy there all you smart reading... )

[Fish Farmer]

Id say 50-1 also, I know when I had my 1961 10HP Evinrude they didn't have 50 to 1 oil, we used 1 Quart of 30 sae regular to 5 GALLONS of gas.

[crappyfisherman]

thanks fellas. makes me feel better knowing im not hurting it.

 

Cheers!

[GBW]

if you can, find out the brand of oil the last owner used. you might not want to start running AMS-OIL Synthetic in it if it's never had it run through it before. If you cannot find out, run the good old style stuff you can get at CTC as that's what was more then likely used in the past.

 

Just my extra to the reply...

[tightline]

definetley 50:1 my buddy has 2 and we run it all the time

[backbay]

The design of the oil dictates the ratio: not the engine itself. Just follow the directions on the container, that'll keep you out of trouble.

[Uncle Buck]

i always run my older motors at 45:1... a little extra just to be safe... cheaper then changing engines...

[Billy Bob]

I bought a new 1975 7.5 hp Mercury back in 1975 and it was 50:1 on the oil. And no it's not what kind of oil you use but what the manufacture recommends that determines the ratio.

 

Bob

[bubbles]

I have that motor, 50:1