What is the best oil to use in a 2004 Honda forman rubicon 500 with the hondamatic tranny

 

Thats a very high tech ATV tranny, I would stick to what Honda recommends.

 

I use Shell Rotella 5W-40 synthetic in mine. It's JASO-MA rated as well.

I understand that Honda recommends 10W-30 in these machines and my 07 Rubicon runs just fine with the Shell oil. I use the Shell oil in my son's 09 Recon and my wife's 04 Bruin as well as the grandkids 06 TRX 90. Let's not forget my Yamaha motorcycle!

Most will tell you to run Honda branded oil so......

 

10W40 for most climates, rated JASO MA and API SG or higher, that does NOT say energy conserving, and nothing with Molly or teflon/ptfe.

Honda's dino oil would be fine, as would their HP without molly.

When I did farm work summers, we ran Rotella 15W40 in everything, including several three wheelers. They ran thousands and thousands of hours. Now that Rotella is rated JASO MA (meaning it is OK for wet clutches, like the Rubicon) I wouldn't have a problem running that, either.

 

I have been using Valvoline 10w40 ATV oil for the last 12,000 miles from -10ºF to +100ºF with no problems.

Beisdes being JASO MA and API SG rated it also has friction modifiers for the wet clutch.