View Full Version : Synthetic Oil in older 2 Stroke Outboard
09-21-2009, 11:34 AM
I have a 1990 115 Merc. which has been a great motor and will have to continue to be and I am due to add oil to the injection tank and wondered if anybody has switched to a full synthetic. I have used the Mercury brand oil (non-synthetic) and had no issues. My last fill was a semi-synthetic brand for "older" motors and has been the smokiest, worst oil I've used. I'm thinking of using Amsoil HP injector since it's easy to get and fairly reasonable in price. I have used synthetic in my weed whacker and chainsaws and seen dramatic improvement in performance and a lot less smoke.
09-22-2009, 12:38 PM
I've found that the "traditional" oil works the best in my outboards. This includes an '87 Mercury 115, a '96 Mariner 5, a '93 mariner 6, and a 2003 Yami 90. I either use the mercury oil or yamalube for the yami, but due to post on this site I've switched over to Sea and Snow. I had the same experience with the Synthetics - smoked like a sun of a gun. I was told that this was just all the "crud" being burned out of the engine. It could be, but I also run a little Sea Foam and never had any problems so I figured why burn the money.
I do have a quesiton for you. Do you use a synthetic in the lower unit? I just started using the wall-mart brand and didn't have any problems - No water, no burt smell. In fact it looked new when I changed it for the winter.
Hope this helps.
09-22-2009, 04:33 PM
Used Citgo in the lower unit and I'm not sure if it's a synthetic or not. You do the same thing I do with the seafoam. The Merc oil is reasonable(found some at Sam's club for $18.00 a gal.) I will be switching plugs-had NGK's in it for the 1st time and don't feel they're as good as Champs or the Splitfires I ran for most of the engine's 19 years. Really don't like the Penzoil Semi Synthetic for older outboards. The sea and snow is semi synthetic, right?
09-22-2009, 04:48 PM
I do beleive that the s/s is semi-synthetic. I don't like the Penzoil either - I've also found that Penzoil fogging oit doesn't fog/foam up as well as the merc fogging oil.
09-22-2009, 07:54 PM
Yes it is semi synthetic.
09-23-2009, 01:04 PM
The Mercury oil is Citgo. I just bought my 4 gallons at farm and fleet today. My friend delivers the oil to where mercury has it packaged and he said it was citgo and they just dye it.
09-23-2009, 02:10 PM
What a rip. No wonder I can't tell the difference.
09-24-2009, 09:24 AM
Oil is oil to a certain degree. I like the cleaner burn and better performance I've seen in my 2 stroke air cooled small motors and hoped to see the same in the old Merc. I am OK with the sea and snow in my sleds and it will simplify my oil buying to just get 1 brand. Hoping to get one last ski in tonight and then get the sleds ready to go. Thanks for all the input...think snow!
09-24-2009, 01:16 PM
A friend of mine has the same engine on his boat and switched to Amsoil HP and has no problems anymore, it helped the sparkplug loadup
and runs cleaner.
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