1987 Mercury 70hp premix oil

brooksville_rebel

Petty Officer 1st Class
Joined
Aug 12, 2011
Messages
240
Finally got the new engine on the pontoon.(old one seized up while out on the water) Its a 1987 3 cylinder 70hp Mercury. The oil mixer has been removed from it so now searching for the "best" oil to mix with the gas. I emailed Mercury and got a reply just saying to use a 50:1 ratio. With this old of an engine is there a specific oil to use ? Synthetic or not ? The ones touted as High performance ? Little confusing as other than my weed wacker haven't done mixing before.
Thanks
Mark
 

flyingscott

Fleet Admiral
Joined
Apr 8, 2014
Messages
8,293
Any oil rated tcw-3 mixed at 50-1 will be fine for your motor
 
Last edited:

RCO

Petty Officer 1st Class
Joined
Jun 15, 2016
Messages
350
You are bound to get lots of opinions any time you ask about oil. As mentioned above anything with the TCW-3 rating will be fine. I like to use the factory Merc oil. It seems to smoke less and smell better to me, and is only a few bucks a gallon more than the generic stuff.
 

MH Hawker

Vice Admiral
Joined
Jul 13, 2011
Messages
5,516
i use the walmart super tech brand at 12.50 a gallon, in a older motor, its going to smoke no matter what you use, add a bit of sea foam ever now and then to clean the fuel system and float on
 

444

Senior Chief Petty Officer
Joined
Jul 16, 2010
Messages
704
Mine's a 1978 merc 175hp. I've always run the cheap marine 2-stroke oil in it. I figure it's got to be the closest to what this thing was designed around back in the day. I've tried the mercury brand stuff as well. Didn't find any difference. I have not tried the synthetic. With the premix you go through more of it than with the injection system so keeping the cost down can be helpful.
 

bwhalerman

Seaman Apprentice
Joined
Jul 4, 2016
Messages
47
Finally got the new engine on the pontoon.(old one seized up while out on the water) Its a 1987 3 cylinder 70hp Mercury. The oil mixer has been removed from it so now searching for the "best" oil to mix with the gas. I emailed Mercury and got a reply just saying to use a 50:1 ratio. With this old of an engine is there a specific oil to use ? Synthetic or not ? The ones touted as High performance ? Little confusing as other than my weed wacker haven't done mixing before.
Thanks
Mark

I run a 1988 70hp 3cyl 2 stroke and use the Mercury Synthetic oil. Haven't noticed any difference.
 
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