I am not an atv guru so I need some information from some guru's. Have a older 250 cc Timberwolf and trying to get it back in good running shape. It has not been used in several years, been setting up. It cranks and runs okay and I plan to change motor oil in it, that's where the problem arises. Was told DO NOT USE AUTOMOTIVE OIL IN IT. Requires mineral oil. Where can I get additional info on type of oil to use? Atv was given to me by elderly lady with no manuals so any help will be welcomed. Thanks Daniel

I run/ran Rotella Synthetic in all of my atvs/utvs. You can run regular non-synthetic and will be fine. Just don't use an automotive synthetic as it has friction modifiers and can cause an ATV/UTV wet clutch to slip.

If you can't find Yamalube use Maxima Maxum4, Atv's run at higher rpm's than vehicles and require better oils. I have owned dozens of atv's and dirt bikes raced in the desert and on ice and high elevations under extreme loads and would not ever skimp a few dollars on the wrong oil.

Your machine has a centrifugal wet clutch, the engine oil lubricates the engine, transmission gears & wet clutch.

The oil you use should have no friction modifiers, which will cause the clutch to slip, jerk, overheat & finally fail.
Usually this takes quite a while to occur, the damage is not often instantaneous, but in some instance it can wreck the clutch material in a few miles.

JASO MA is a Japanese standard for oils which are used in 4-stroke motorcycle engines with one oil system for the engine, gearbox and wet clutch system.
Jaso MA signifies the fluid is non-friction modified.
Jaso MB is friction modified but contains less than a typical spark ignition 4 stroke motor oil.

As long as the oil you use is rated JASO Ma, Ma1, Ma2 or non friction modified or compatible with wet clutch it will work.
If it doesn't say Jaso Ma on the bottle you can look it up on the oil brands web site. There are several to chose from.
Yamalube performance all purpose is one.

Base stock has no bearing on if the oil contains friction modifiers. Friction modifiers are added to oils.
The mineral oil only caution comes from a time when non friction modified mineral based oils were common.
Friction modifiers and wear protection additives are not at all the same thing.

There is nothing wrong with using synthetic, semi synthetic, petroleum, mineral - whatever - as long as it doesn't contain friction modifiers.
Most automotive motor oils do, that's why using a 4 stroke motorcycle oil designed for wet clutch applications, or an oil that specifically states compatible with wet clutch / labeled JASO MA is recommended.

Believe or not there are a ton of folks that won't believe any of this and dump in a quality regular motor oil and their machine survives for years.
There are also tons of people that use the wrong products when doing routine maintenance it causes a failure and they blame the manufacturer for building junk.

The whole changes in API rating thing over the years is an outrageously convoluted & very complicated mess.

Rotella T6 synthetic is what I run in my street bike and used to in my ATV when I had one, it's JASO MA rated. It is an oil primarily for diesel engines but is easily available at any auto parts store, and even some Walmarts. Cheaper than Yamalube.

This what you need for your Yamaha. Wal-Mart has is.

https://www.walmart.com/ip/Valvoline-4-Stroke-ATV-Conventional-10W-40-Motor-Oil-1-Quart/19514362

That's what I would use, but I put it in my truck and every other small engine I have around the house.

If it's aircooled and 4stroke, it gets Castrol GTX 20W50 - been using it forever in street and racebikes and Honda ATVs with automatic clutches.
It stands up to the extra heat of turbocharging and works well in aircooled engines since they run hotter than water cooled.

I used the Rotella for a few oil changes. Used some of the Honda oil for the most recent change.