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what weight oil/ what kind

4 posts in this topic

I have a yz400f 1998, I bought 4 quarts of motorcycle oil, 15w 50 because i found it on sale and i was planning on using it until somebody told me it needs to be like 90 degrees f to use or its to thick so i am wondering if i should use it or not it is around 50 degrees in wi right now i am currently running 5w 30 last summer i ran 10w 40 so what should i be using and what is the weather i should be using these in 

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Attached is a typical oil range chart from the manual.  Note that 20w-(X) is good for temperatures down to as low as 50 ℉.  10w-(X) covers temps as low as 10 ℉.  On the up side, (X)w-40 is usable in weather up to 110 ℉, so there is rarely a reason to run 50 weight oils at all, although I personally use a 20w-50 during the hottest 3 months of the year in SoCal (July-Sep) when temperatures are at or above 90 ℉ most of the time.


50 weights are unnecessary in cooler weather, and I almost always run 40's because the lighter oil circulates faster, and the volume of oil delivered to the lube points is more important than how thick it is. 


Use a premium oil, preferably a true full synthetic blended for use in motorcycle engines that share engine oil with the clutch and transmission.  Change or service the filter every time you change the oil.


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