so I decided to google the pros and cons about synthetic oil.
Given that my believe about Synthetic oil is based on info learned about 30 year ago and hoping that the makers of Synthetic oil would want to make their product better-- I'm going to give synthetic oil another chance on my next oil change. I know my TM behaves a certain undesirable way when its time for an oil change. Since Synthetics are advertised as being able to last longer between oil changes, I will wait longer to change the synthetic oil. If my TM starts to act up near the 100 hour mark I will know Synthetic oil is not for me. I would hope I could go 150-200 hours on synthetic.
I don't live in a cold nor hot climate--"google" says Synthetic oils perform better in cold weather-- so maybe synthetic should be used for most of you guys.
I wouldn't be concerned with how much longer it'll last between oil changes. I have a liquid cooled engine also, and I still use the rule of thumb to change every 50hrs. I know what you're describing when you're talking about how the engine "starts to act up". It starts getting louder and sounding rougher on cold cranks.
It's some MAJOR dangerous friction inside the engine due to the oil wearing down. And it's causing damage that I can't describe because that's where the little oil leaks, and internal burning of the oil starts.
Changing 3.5quarts of oil and an oil filter once a month is very cheap whether you use synthetic or normal motor oil. If you want your engine to last over 2000hrs, I suggest it.