Synthetic vs 2 Cycle Oill

I run an older OMC 90hp with oil injection. Also have a older OMC 9.9 kicker (mixed gas). Every now and then Amzoil is mentioned in posts.

Questions:
1. Can I run a full synthetic on these motors? Pro’s – Con’s?

2. Will the oil injection on the 90hp be consistent if I replace 2 cycle oil with synthetic?

3. Are other synthetics, e.g. Mobil 1 a possibility vs Amzoil?

Thanks

Pete

Mobil 1 isn’t a 2 cycle I believe? so you can’t run it in a outboard
Stan

I have been running Amsoil HP in my 93′ yammi 60hp since I bought it in 06′. I run 3-4 gallons a year in it.
Since then its all I use for 2 stroke oil.
You can mix it or inject it. You should have no worries switching over.

As far as pros/cons. Synthetics offer greater lubrication and higher viscosity. The only thing I have “heard” not to do is switch back to mineral oil after going to a synthetic. As mentioned it may be here say…

You can run 2 cycle synthetic in it. I would think the only reason for suggesting not to switch would be the synthetic manufacturers wanting to keep on hooked. If one is using oil injection, then maybe there could be something related to whether conventional and synthetic might not mix as I have see this on labels for my snowmobile oil, but I would think as long as one runs the oil tank nearly empty and then adds the other, it should work just fine.

I went to Amsoil 2 seasons ago in my 93 evinrude kicker and it starts much better in cold weather and the smoke is far less. I’m not looking back

The best thing about running 100 percent synthetic is there is little to no carbon build up in the exhaust ports or the rings. I blew my fair share of outboards running dyno oil because of the carbon build up from the oil and sticking the rings.

As others have said, Mobil 1 is not 2 stroke oil. There are other full synthetic 2 stroke oils out there beyond Amsoil.

Pros:
– Synthetic oil offers the ultimate in low-smoke and fouls the least at low RPM.
– Protection is good to excellent.

Cons:
– The cost.
– At high speeds where combustion is more complete, there is little difference in smoke between regular and synthetic.
– There are conventional and semi-sythetic blends that offer as good of protection at half the cost.

I’ve torn down outboards, chainsaws, and other 2 stroke equipment that had been run for decades on conventional oil and if the owners used good fuel AND didn’t overmix the oil, the engines look great.

Personally, I don’t see any reason to start using full syth in an older outboard unless you are doing a lot of low-speed trolling and want to reduce smoke to the lowest possible level.

For injector oil, I’d look at a semi-synthetic like Pennzoil XLF. Less than half the cost per gallon, excellent protection, lowest smoke of any convtional oil I’ve used, and readily available.

Nothing wrong with synthetic, I’m pretty much addressing the cost to benefit ratio of switching over an older outboard.

Grouse

Thanks for the info Grouse . Now on my 89 Johnson 60 HP would it hurt to switch from running the oil I use? I am using bulk Evinrude/ Johnson 2 stroke oil. Motor is oil injected. Thanks.
Shawn

Great info guys and to the point. Got an old 15hp that will be getting switched now as my main motor and back trolling the smoke can get annoying, the less the better and I will pay the price.

Quote:

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Thanks for the info Grouse . Now on my 89 Johnson 60 HP would it hurt to switch from running the oil I use? I am using bulk Evinrude/ Johnson 2 stroke oil. Motor is oil injected. Thanks.
Shawn

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No it will not hurt. There is no truth to the myth that somehow manufacturer-label oils are superior to other oils.

2 storke engines can run for many, many decades as long as they are well maintained and good oil and fuel is used. I persoally have a 1985 25-HP Johnson that has been run for thousands of hours. It’s been flawlessly maintained by both me and the previous owner and despite being 30 years old, the compression is at as-new levels. This outboard could easily be running at 50 years old without ever having even a top-end job.

And whatever you do, do NOT let any armchair generic mechanic talk you into tearing out the VRO system and going to premix. There is a lot of urban legend carpola out there about VRO systems “causing” engine failures. All of it is proferred by amateur shadetree hacks who don’t actually know anything about how oil injection systems operate.

Also, what you don’t hear about is what happens when generic mechanics tear out VRO systems and then forget to premix their fuel. They never own up to that on, but I know it’s happened.

Grouse