Questionable?
The old oil debate again.
I'm going to throw something out.
I have a 96GTI, I bought it from a friend of mine, who purchased it new.
He had always used, since the ski was new, and I have continued to use; "Castrol Super Outboard Motor Oil". This is the oil that the dealer recommended back in 96.
The oil was developed by Castrol especially for SkiDoos and SeaDoos, and was approved by Rotax for use in their engines. The oil is manufactured in Canada.
The ski is 14 years old and I have never had to work on the engine or had engine work done. It had the original spark plugs until the year.
The oil is mineral based, and I think that it is no longer manufactured. The last case I bought I had to mail order, but it was only about $3.50 a quart.
Lou
Your statment about no work being done is kinda hard to believe, since in 96, all Rotax motors came with the grey Tempo fuel lines. If these are not changed, or even when you decide to change them, you have no choice but to go through the carbs and clean out the dissolved solids of these old fuel lines.
I'm pretty sure you aren't running the same plugs, since the electrodes over time erode. Over time, they will also build resistance and will decrease overall fuel range. You did come back and state you've only had it two years. So, I'm here to say that I'm positive these plugs are not original.
I'm also going to tell you that the oil you are running is not the recommended oil that BRP and Rotax requires for motor longevity. That Castrol oil is a TCW-3 oil. These oils are formulated to run at any rpm without fouling plugs. Our motors require an oil that maintains lubrication at variable rates of injection.
For this thread, please, only use an API-TC rated oil that is non NMMA (national marine manuafactures association) or TCW-3. TCW-3 is designed as a premix and easily disperses itself throughout the fuel tank when mixed. We inject our oils, so to use an oil that is designed to be mixed, isn't appropiate.
When you idle the Rotax, the injection pump is probably at a ratio of (theoretically speaking) 80:1 and when at WOT, about 50:1. The variable rate injection pump is designed to use just the right amount of oil in our engines for lubrication with a minimal amount that needs to be burned off.
If you use a TCW-3 oil, smoking, carbonizing and carbon fouling plugs will be normal, so carry a spare pair of plugs. Also, the TCW-3 oils used in outboard motors usually allow you to set your outboard up for different heat ranges. If you use the boat for slow speeds, trolling for fist, you'll want a hotter burning plug, to help burn off the excessive oil. If you use that motor for skiing or mostly WOT running, you'll want to burn a colder plug, since heat from running at speed will help to keep combustion occuring easily.
Don't use a TCW-3 oil in your Rotax. Yes, it will work. But, it will, over the long haul, reduce the life span of your motor.........:cheers: