2 days ago I changed out my Lucas 10w40 semi synthetic for full synthetic 10w40 Amsoil motorcycle oil after hearing all this hype on Amsoil I want to try it in my quad to see if it's worth it or not to invest in it for all my vehicles. Anyway, I am a big anal retentive about it because it's supposed to be the top notch oil out there. Today I went for about a 20 minute ride, enough to get the engine up to operating temperature and keep it there. Anyway, when I got home I pulled the dipstick and noticed that the oil on it had a bunch of bubbles on it and I could see foam around the opening of the oil tank as well. I don't know if my Lucas ever did this as I never pulled the dipstick after it had been running before. I just need to know if this is a problem I should be concerned about. At $13 a quart, I sure hope not. Other than that, I like everything so far about the way Amsoil works. My engine quieted down a bunch and shifts smoother than ever, it seems to have more power response and pulls harder too.

2013 Honda 400X is what I have, I am the original owner and it's completely bone stock if that helps.