The following is a little information on the correct oil for the Rincon and some different oils that are out there. I'm sure that I won't have every oil that will work in the Rincon listed, but I will have the most commonly used oils. These are oils that Rincon owners have been using since day 1 and are proven to work well. If I miss one, feel free to add it to the page.
This is from the service manual for engine oil specs: "Pro Honda GN4 or HP4 (without molybdenum additives) 4-stroke oil (USA and Canada), or Honda 4-stroke oil (Canada only), or an equivalent motorcycle oil API service classification SG or higher except oils labeled as energy conserving on the circular API service label. JASO T 903 standard: MA."
Most ATV/motorcycle oils designed for use with a wet clutch will have this certification. Although there are some oils out there, like Rotella-T synthetic, that do not have this cert. but will work fine.
You should also pick an oil weight matched to the climate you are in. Hot climates use a heavier weight oil and cooler climates use a lighter oil. The following is a chart from the Rincon service manual.
For starters, Honda makes two oils for the Rincon. GN4 is a mineral oil and is probably what is in it from the dealer. There is also a synthetic oil, HP4 from Honda. Make sure you get the HP4 without molly, or you are going to have some issues!
As stated above, Rotella-T 5W-40 synthetic will work fine in the Rincon. It is not a ATV/MC oil, but it does work. It is in a blue jug and can be found at Wal-Mart.
Amsoil has several synthetics to pick from. The Formula 4-stroke 0W-40 (AFF) is commonly used for the Rincon.
They also have a 10W-30 Formula 4-stroke small engine oil (ASE), 10W-30 (MCT), 10W-40 (MCF) and 20W-50 (MCV) Motorcycle oils. The Premium Protection 10W-40 (AMO) and the Premium Protection 20W-50 (ARO) oils are also JASO MA rated.
Another popular oil is Mobil 1 Racing 4T 10W-40, formerly MX4T.
Spectro has a number of oils to pick from. Spectro Platinum 0W-40 is the most talked about of the Spectro oils. Info on Spectro can be found here...http://www.spectro-oils.com/products.htm
The oils above aren't in any specific order, just the order that I put them in. As I stated above, this is by no means a complete list of oil for the Rincon, just the most common ones. Some are synthetic and some aren't.
Weather you pick a synthetic oil or not make sure you match the weight of the oil with the temperatures where you live. Copy and paste the link above to see the chart if you don't have a service manual.
Also keep in mind that everyone has their own preference for oil and it's up to you to pick what you want. All of the oils listed above have been used by many and one may not be much better or worse than another, you can't go wrong with any of them. It will probably come down to what is readily available in your area. As always, follow the recommended change intervals from Honda.
mudbud 2006 camo rincon, kimpex buddy seat, 2.5 warn winch, warn front bumper, atv-guru rear bumper and combo hitch kit, high lifter springs, VTR spring spacers, garmin gps, Stewert Warner Temp and Volt gauges, swisher heated grips, itp terra cross rt's, full AP skid plate setup ~ 2007 Foreman power steering and ESP for the wife, Warn RT25 winch Aluminum Products skid plate hook holster, skid plate and stick guards Warn front bumper Home made rear bumper a atv guru knock off. Moose heated grips and thumb warmer, Cycle Country plow.