51 Re: Engine Oil Sat Apr 06, 2019 10:38 am
Point-Seven-five
Life time member
As a matter of fact the film strength on the Quaker State oil is pretty good. The film strength number of 113,377 psi at 230F(normal operating temperature)puts it in the top 10% of the oils tested. Not only that, but at 275F(overheating temperature) the film strength only loses 3.7% of it's value down to 109,211 psi which is better than 191 of the oils when they were tested at the 230F temperature. In other words, the Quaker State film strength when overheated is better than 191 other oils at normal operating temperature.nobbylon wrote:If 5w30 was correct for this motor then surely it would be the recommended grade. This chap actually states that a heavier grade is needed by aircooled motors and to me the K is a hybrid of water and air cooled. The recommended grade for these in Western Europe is 10w40 in winter and 15/20w50 in summer. The film strength on this 30 grade better be good otherwise you wont be protecting anything if it overhears. Seeing that many K’s have 100’s of thousands of miles on them, how many more 100’s will wonder oil do and how many of us will actually use the bike for those miles?
My RS has done 55k miles from new. If I last another 25 years doing 2k/year which is optimistic then my RS will have approx 100k on it when I’m 80! Do I really need wonder oil or to be even bothered about it?! Just throw in some 20w50 every 3-5k and free your mind of another oil saga.
As the author states, the film strength is the only real spec that tells how the oil is going to prevent wear. Viscosity is resistance to flow, and the author says that higher viscosity causes more wear at start up because the resistance to flow starves wear points farther from the pump. Centistokes is the unit of resistance to flow. He has posted these numbers, and strangely, the centistokes value has little relationship to SAE viscosity numbers. The Quaker State oil has good numbers here as well(thin at start, but not overly thin at high temperature), and like the film strength, viscosity stays more uniform as temperatures rise, doing a better job of maintaining the hydraulic wedge between parts.
If you don't have the time to read the first third of the article, just skip to the numbered articles in the last half. The titles are pretty self explanatory, and if you skip the resume and testing methods boilerplate at the start of some of the articles you can quickly get to the meat of the article.
I think I will be making a list of the top 25 or 30 oils with their pressure ratings and viscosity numbers. This is mostly for my own use, but I'll post it here for anyone who may be interested.