Oil weight confusion

Alright, so I've been running the Mobil 1 racing 10w40 in my 2010 yz450. I've been thinking about running amsoil in my truck. Figured I'd become a preferred costumer and go ahead and get oil and filter for my bike. They recommend 20w50 for the 450.....the only 10w30 I can find on their site for use with wet clutches is their scooter oil. Not sure which weight to run or if the scooter stuff is really for high strung engines....

I don't think I saw that on their site earlier but I had thought about running Mobil 1 0w40 in it. I never did and can't remember why I was going to lol so, amsoil 0w40 is alright to run in me yz450?

Yes, it is perfect for the 450. I have been running it on my bike for the last 45 hours and not one problem yet.

Redline uses a better base stock and a more robust additive package.

I'm not here to argue about what oils are better. There are a ton of threads about differant oils. The guy asked about amsoil and I answered him.

Yeah, I just didn't know why their site recommended 20w50!

I use the 10w-40 AMSOIL religiously!

I use the 10w-40 AMSOIL religiously!
the scooter oil? Lol

20w-50 can be used if it's warm enough outside, and I use it through the hottest 4 months of the year, but otherwise, it's 10w-40 year-round.

Both companies offer some of the very best available oils blended specifically for extremely high performance four strokes that share oil with the transmission.

Amsoil offers 3 oils specific to your bike:


Mobil1 only two, 10w-40 Racing 4T and 20w-50 V-Twin, both linked at the left of this page:


They are excellent oils and I recommend them. ANY OTHER oil that either of these two companies produce is subject to the suspicion that it doesn't have the correct additives to allow it to survive as a gear lube for any serious length of time, regardless of the fact that it may be a fine ENGINE oil. The problem is the oil for bikes such as this need to be able to do both jobs, and most oils made by most oil companies won't. Most of the better ones do make a couple of oils that do suit the task, but again, only one or two.

Oil weight recommendations are listed in your manual, and are dependent on the ambient temperature range. Oils with a weight listed at 10-(X) are OK down to 10 ℉ (-10 ℃). If it's warmer than that where you ride, don't worry about it. That cold or colder, use a good 5w or 0w, and change it often.

Thanks guys. I've only used the Mobil 1 racing since I've had it but figured if I was gonna pay to be a preferred customer, I might as well get as much oil as I can :-)

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