Jump to content

  • Join Today, It's Simple and FREE!

    As a member, you can post in our forums, upload your photos and videos, use and contribute to our downloads, create your own member page, add your ATV events, and even start your own ATV club to host your own club forum and gallery.  Registration is fast and you can even login with social network accounts to sync your profiles and content.


1990 Yamaha Big Bear 350 - Engine Oil Questions

Recommended Posts

Hi All,

I will start by saying I am real new to ATV's but not to wrenching. I just completed a complete fluid change on my 1990 Big bear 350.

The owners manual recommends 20w40 for the engine oil but I see nearly everywhere people using 10w30 or 10w40.

I actually was unable to find 20w40 so I used 20w50 that I did find at Walmart.

My questions are:

1) What is the Statndard that is OK?

2) Is regular oil for Automobile OK to use?

3) Whats the difference in Auto oil vs Motorcycle oil vs ATV oil? Is there any?


Share this post

Link to post
Share on other sites

you have to use atv oil, there are additives in the oil for the transmission. 10 40 is about standard. i would go to synthetic myself, doesn't take much to fill the crankcase, so it isn't as expensive as a car oil change. you could even go 5 40 or 0 40. the lower the first #, the easier it is to crank over. the higher the second #, the heavier it is. 0-5 40 would be good in cold climates, and 40 weight is about standard ...

Share this post

Link to post
Share on other sites

if you put car oil in, you jepordize the clutch. just saw your last post. car oil will be ok for the engine part of it, but may give you a false reading that the clutch slips etc...

Share this post

Link to post
Share on other sites

Thanks for the info!

Let me follow up with this one building on my other post. In a nutshell, due to the amount of shavings found in the oil filter on the oil change I just did, I fully expected to do another oil change after running for a few miles just to validate a clean engine.

Do I risk any damage running for a short period with the 20w50 I have in there now?

Share this post

Link to post
Share on other sites

you will only risk the clutch, but it really shouldn't do damage, it just won't help it ...

that's just if you're putting around and not working it hard ...

Share this post

Link to post
Share on other sites

thanks again!

not really working it since it has been unused for so long I've been mainly giving the kids rides around the yard so far.

This weekend I'll get the proper ATV oil and run thru another change.

Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Similar Content

    • By Arctic Snowdog
      Hi Guys,
      I have a small Sled Dog business and I train up to 14 Huskies pulling a Yamaha Grizzly 550, that is quite a lot of Horse (Dog) power. Sometimes in order to make the ride smoother for Dogs and us we ride in Neutral but on a few occasions I have noticed that the right hand (front) brake seems to loose pressure and does not brake at all. Is there a particular reason for this ? Is it a fault or is it something to do with us riding in neutral, I only use the ATV in this way a few months a year before the snow comes but I am sure I recall the same thing happening last season.
      Any ideas would be greatly appreciated because I am a far way from being a mechanic.....
      Have a super day and thank you all.

    • By Wiktorix Gameplays
      Can I use an old snowblower engine in my 90cc quad? The old one blew up. 
      Thanks for the help. 
    • By Jacob Blocker
      I have not been able to start my 300ex that I just got off a guy. I was able to getting it running once, then never again. After a week of trying to make it run I got a compression tester and it is saying about 30 psi. Is this definitely the rings just worn out or can it be something elses? I can't even make it pop when I spray stater fluid in it.
  • Recently Browsing   0 members

    No registered users viewing this page.