i used 10w30 in my ranger gxt and used oil as a new machine
changed to straight 30 wt. and i quit using oil....go figure. i have had good luck with 30 wt.
Are You changing the oil after the machine has been up to operating temperature for a while? You should be in My opinion, because the oil is thinner then and will drain more quickly and more completely. If it doesn't crank fast enough to start in cold weather with 30 wt, I would go to 10w30 for winter. Some of the dirt in the oil is metal particles that wear off the moving parts inside the engine, the rest is carbon from blowby past the rings. Both are normal and may decrease as the motor wears in, and then blowby will increase as the motor wears out.
I run fully syn in my trailblazer after my buddy told me his quit using oil when he switched from reg to syn, I did and quit using oil too. I still use str8 30 in the winter and it starts just fine, in N-WI it gets pretty coldup here. but no problems.
I have an older model of the same engine (onan - robin) . Dave Boyer is correct about what is happening in your engine while it is not broken in yet. After my first 100hrs I switched to Briggs and Stratton 30w fully sythetic. Its hard to come by , but most small engine suppliers carry it. I change oil and filter every 100hrs and I get great results here in south florida where it gets really hot.
Thanks gents, I'll switch to 30 synthetic. I was changing it cold and that little valve that's on the end of the drain hose may have had something to do with the slowness as well.
jws, I've spent some time at Okeechobee jerkin crappie, and trout out of Everglades City and it was hot in January so I can't imagine what it's like in the summer- Thanks-Ted