I was told by my dealer to use 92 Octane on my kids 05 SP90. So thats what I've been doing. With only about 25 cents difference in price between that and regular, I thought why not. Then someone told me that running the higher octane makes the engine run hotter, thus producing less power. I never did ask my dealer why it was that he suggest higher octane. I know that in my truck I use regular until my truck starts to ping or knock. Then I run the next grade up until the ping goes away and then back down to regular. So what is everyone else using. I think that the next time I feel us I will just put regular and see how that goes.

 

Higher octane helps prevent predetonation which can cause a hot spot on your piston. In more severe cases, it can even burn a hole in it. What octane you should use is dependent on your engine's compression.

 

Your Sportsman 90 has the lowest compression of any motor you'll ever find that will run. They have about 90-110 psi compression. Reg 87-89 is fine. Wont detonate. Run whatever you run in everything else. Just run a good oil.

 

I've got a tank of 92 octane in it now. I'll go through that here in the next month and from here on out run just 83. It has polaris oil in it now. It's blue. I bought a bottle of gold when I got the machine. Havent had to add any yet. My oil light kept blinking so I took it in. They said the sensor was located to high so they just added more blue oil to it. I check the oil level each time before we go out. So I'll wait until the oil goes down before I add the gold. Not real sure about mixing the oils even though they are both polaris. I've really liked this machine for the kids.