How about the 50:1 oil/fuel ratio in older outboards

[John Reynolds]

How about the 50:1 oil/fuel ratio in older outboards, like my 1956 Mercury mark 55E? The owner's manual etc. say 25:1. But with modern oils after nearly half a century's worth of technological improvements in lubricants, should a person use less oil? Perhaps something in between 25:1 and 50:1? They didn't have TC-W3 back in them days, and the motors must be designed for poorer lubricants.

 

[almost retired again]

Re: How about the 50:1 oil/fuel ratio in older outboards

Hello John;<br />I have in some notes that I took in one of the schools that I went to back in the 70's that says that you can use a 50/1 oil mix in any outboard that OMC made if you first decarbon the engine. Since then I have followed this advice many times without any ill effects. However if you feel squeamish about it, more oil won't hurt it.<br />Good Luck

 

[alcan]

Re: How about the 50:1 oil/fuel ratio in older outboards

Hi John<br />Run what you want. Remember the fifties was the golden age of outboarding, it was also the nucular age,jet and space age, not the stone age. I believe that the reason we have so many fifties model outboard around today is due to the amount of oil used. It didn't take OMC too long to figure out we as consumers wern't about to put with the 100:1 ratio and blowen up motors.The basic outboard design has not really changed since the fifties. They just keep adding modern control componets. Oil is a coolant, greese is a lubercant.

 

[John Reynolds]

Re: How about the 50:1 oil/fuel ratio in older outboards

Perhaps everyone should use 25:1? I guess as long as the oil doesn't leave to much residue then perhaps it might be a good thing? (besides the added cost of the oil, ha)

 

[steelespike]

Re: How about the 50:1 oil/fuel ratio in older outboards

Ask at Johns old mercury web site at:<br />www.pfs-ware.com look for the forum and many excellent links. <br />As far as OMC 50 year Evinrude dealer told me 50:1 on larger motors back to 1960.I took larger to mean 35 hp up.I should have asked specifics.

 

[Alwsfishin]

Re: How about the 50:1 oil/fuel ratio in older outboards

Hello all.....just found this great site....<br />I have 7 50's outboards ...I run a 1959 35 Johnson on a 16 1/2 1959 Lyman...I cannot get this to run on 24:1.....It runs great on 50:1....or a l'il richer.....but 32:1 to 24:1 .....forget it....Joe Reeves tells me 50:1 is ok ....but a 50 yr exp outboard mechanic tells me 24:1 only...he also says that the gas today with ethanol & alcohol can tear a motor up...so you should use the vry best oil additive .....I switched to Evinrude Ram 2 cycle....its a l'il pricy 15.00 to 25.00 a gallon

 

[Lark40]

Re: How about the 50:1 oil/fuel ratio in older outboards

When you can't get the engine to run as it was designed to, you've got something wrong.<br /><br />I've had several 1959 35 hp engines, going back to uncrating them in Fall 1958.<br /><br />Sure, it's embarassing sometimes when I start up my 1960 Lark at a public dock and smoke up the place with a 24:1 mix, but I know I can run it hard all day and not blow anything. <br /><br />Maybe a 32:1 mix is perfectly fine on the larger 1957-1963 OMC engines with roller bearings. But, I've been running this series of engines for 45 years, and nobody has convinced me that 50:1 is in my best interest.

 

[John Reynolds]

Re: How about the 50:1 oil/fuel ratio in older outboards

I decided to use 25:1 and consider the advantage of having modern TC-W3 an improvement and additional protection.

 

[Chinewalker]

Re: How about the 50:1 oil/fuel ratio in older outboards

Hi John,<br /> Your Mark 55 has either aluminum or bronze center mains and it NEEDS the extra oil to not only lubricate, but to seal between crankcase cavities. I've got a bunch of reed cages with scorched centers due to running lean on the oil. However, because the motor has needles, rollers and ball bearings at all other points, you can lean it out a bit. I ran my 1961 Merc 400 on a diet of 32:1 and all crank journals were perfect when I did a teardown after the intake sucked up a bag and cooked the top piston. Quality of fuel and oil plays a big part in it, too. Don't scrimp!<br />- Scott

 

[John Reynolds]

Re: How about the 50:1 oil/fuel ratio in older outboards

Thanks Chinewalker, you sound like the man to talk to. What fuel/brands do you reccommend? Thanks

 

[Chinewalker]

Re: How about the 50:1 oil/fuel ratio in older outboards

Hi John,<br /> In my racing Mercs I run Amsoil at 24:1, but in my service motors I run my old Mercs at 32:1 with OMC's basic TCW-3 oil. I prefer to run my stuff (racing included) on 89 octane as it's tends to be a bit more consistent in quality. Because the old Mercs tend to run cool anyway (no t-stats), I feel it's better to run the lower octane grades in them. If you've got a good source for 87, go for it. Avoid alcohol blended fuels.<br />- Scott

 

[John Reynolds]

Re: How about the 50:1 oil/fuel ratio in older outboards

Thanks Chinewalker for the info.<br /><br />I wish I knew what and where a good source of 87 octane is. I always buy major name brand for everything (cars, generator, etc.) but the manufacturers don't like to tell you what's in it from what I've experienced.<br />What do you think abnout Wal-Mart's TCW-3?