Synthetic Oil vs Mecury Oil

[debbeeschindele]

We have a mecury outboard 25 horsepower motor. We have problems with the plugs fouling when we use it for a lot of trolling. Would synthetic oil be ok to use instead of mecury brand oil? Anyone have any experience as to whether this might help solve the probem?

[Havin' Fun]

Is it oil injected or mix? Or is it 4 stroke?

I would imagine that your running to rich if your plugs are fouling. Check you mixture.

I just switched to Amsoil in my 4 stroke but haven't run it enough to tell the difference if any.

[Surface Tension]

I'll post assuming its a 2 stroke and your mixing the gas/oil. Switching to synthetic oil won't fix the problem but might get you around it. I'm not sold on synthetics because there is no independent studies or tests on it. You can go to their web sites and read how wonderful it is.
If your fouling plugs theres a few things you should rule out and thats the gas/oil ratio and correct plugs. Next I would go to the low speed adjustment.
Once you get it to were your not fouling plugs then decide on what oil you to use.

[debbeeschindele]

The motor is a 1999 Mecury 25 horsepower 2 stroke. The mixture is 50:1. We only have a problem after using the motor for long periods of trolling at low speeds. We did try different plugs which worked for a while but then the plugs fouled again after a full day of trolling.

[Surface Tension]

Have you tried the Idle/Low speed adjustment.

[ChuckN]

I switched to Amsoil injection oil in an 115 Johnson outboard I once had and I noticed a big difference in performance. I could troll for a long time and hit the throttle and it would go without hesitation. With the TC-W3 oils the engine would "load" up and bog out before hitting high RPMs and planing up. The smoke was unbearable with TC-W3 oils, synthetic it was MUCH better.

If you buy the synthetic, try to avoid the injection 50:1 oil. I believe Amsoil sells the "pre-mix" kind.

I've heard a few people using the 100:1 pre-mix oil, and had success, but I wouldn't do that myself....best to have too much oil than not enough.

It also sounds like your carb(s) are out of tune if fouling plugs that much.

[Ole1855]

Good question, I just bought a boat with a Merc 175 EFI and I was wondering what all of you use as oil? The guy I bought it from used the Merc. brand oil and I was wondering if that's the best for this motor.

Ole

[trollingforeyes]

debbeeschindele: Amsoil sells the 100:1 premix @ $7.90 qt. and it will not load up. I recommend the checks in the above posts also, as it is some good solid advice. One other suggestion is that you bring the boat back to the dealer and have him syncronize the carbs if that Merc is running more than one carb. My dealer did this on my Rice Burner and it made a huge difference in trolling.
For the Merc 175 EFI Amsoil has the 2cycle injector oil. You may wish to give it a try. On oil injected motors is is best to let the oil tank run till it is low on oil before filling with the synthetic oil.

[This message has been edited by trollingforeyes (edited 04-14-2004).]

[Paul Waldowski]

I want to give Amsoil a try in my 2 stroke motor so I would need the injected kind. Where can I get this in the metro area?? I have heard a lot of great things about it and want to give it a go

------------------
Paul
Drake Motel

[email protected]
Marcum
Otter Outdoors
JR's Tackle

[musky hunter]

I have had a similar problem on an older Merc 50 hp. Several things to check. A newer motor shouldn't be fouling the plugs rapidly, if it is, you may have a loss of compression. Easy to check, expensive to fix. Assuming the compression is ok and it still fouls, take this approach. Switch to Splitfire marine spark plugs. These have given me the best results. Then, run Amsoil 100:1 synthetic. I've had no engine problems doing this and believe it works because less of it burns than regular 2 cycle oil.

[ChuckN]

Hey Paul, you can get Amsoil at Fleet Farm.
They changed the specs on it a bit and made it more in tune for outboards. It should be $19 a gallon.

They also made another oil specifically for snowmobiles now for $24 a gallon.