Originally Posted By: MotoTribologist
Originally Posted By: alarmguy
Originally Posted By: alarmguy
MotoTribologist said:If a 10W-60 shears out of the SAE 60 grade, it does not meet the JASO specifications it claims to meet. Some of the grades have some leeway, but above an SAE 50, they need to stay in grade.
If they were planning on SAE 30 or 40s to be used, they would specify those grades; since again, the specifications do not allow that much shear to occur.
By that logic, manufacturers that specify 10W-30 are really planning on the bike running on SAE 16? The idea is for an oil to have as little shear as possible. Shearing potential is not engineered into an oil in order to end up with a different grade.
I dont disagree on paper with your thinking however the facts will never pan out.
Ill go out on the line and say you will never find a 10/60 that will not shear out of grade in a shared sump engine. There is no question in my mind manufacturers take shearing into account, and if they do not, it doesnt matter anyway, why?
Because all shared sump engines shear oil out of grade, some worse then others, but they all shear the oil. Its common knowledge in all the UOAs posted on this very forum.
You will find, every time, the oils with the largest spread ex, 10/60, 5/40, 10/40 oils (in that order) will ALWAYS shear faster then a 20/50, 20/40. 10/30.
I dont care what Jaso states or anything else happening in a lab, the above results are right under motorcycle UOAs in this forum. You will also find in the UOAs that many conventional oils hold up or shear less then exotic expensive synthetics and synthetics in general.
Its not what the oil is made of, its the spread between the high and low on the bottle. 5/40,10/40,20/50.
Its all in the UOA section of BITOG. Nothing in the world would convince me the maker of the bike doesnt understand this concept because it happens in EVERY shared sump and it does not matter the cost of the oil or type of oil, syn vs conv. Its the spread between the numbers.
Bottom line, all is good if your following the owners manual recommendations for what viscosity's, THEN if your into this, research and find the best one to stay in grade and work best for you.
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