2008 Yamaha yZ450f oil

[Yz450Sam]

The previous owner of my bike ran rotella 15w40 in my bike. It's perfect for me being I own a powerstroke and have plenty of diesel oil. Wondering what the good and bads are? Have had mixed reviews. Bike currently just has Yamaha oil in it.

[DFISH]

I've heard of running Rotella T also and have thought about putting it my 2008 450 XCRW. I like the price of it compared to Motorex 10w50. I talked to the guy at the KTM shop and he said it's safe to run but once you run it you shouldn't go back. I'm still curious to know if it's safe to run.

[Jackh1466]

The guys at Rekluse Clutches swear by it.They say don't even use the synthetic as regular 15-40 ok.Im wondering if 15-40 isn't best as my KTM 500 has a temp gauge on radiator and for Dual Sporting hardly gets over 150, But on tight trails fan kicks in at 195 and even then never over 205.10-50 may may be too thick but can you go back if it's had 20-50 .Need expert opinion !!!