Quote:
Originally posted by Hugh R
Ed
I've been reading the same thing. Apparently with flat cam lobes such as mine, its a problem. I've been told to go with a 15-40 diesel oil such as Valvoline or Mobil.
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I don't know if this will help but it's worth sharing.
The wear characteristics of oil are exposed through what's called a four ball test.
http://www.zag.si/~jank/public/bmw/oil_bible.pdf
"FOUR BALL TESTING
Don't forget about the Four Ball Testing, though. Even though this information is sparse, notice that in
the cases where a Four Ball Wear Scar comparison is possible, oils which have higher flashpoints and
possibly even higher viscosity indexes sometimes show more wear on the Four Ball
(This may explain the issue with some of the newer oils, including some synthetics - RM)...."
Then......
"You might get somewhat discouraged by the above statements because they seem to indicate that
there is no way to be sure that you've found the best oil, even if you think the oil has the best numbers.
To some extent you are right.
However, keep in mind that the numbers below make it clear that synthetic oils are, by and large, far
superior to petroleum oils. So, by choosing any of the synthetics listed below, you'll be purchasing
enhanced protection for your vehicle.
In addition, to help out a little, in the electronic version of The Motor Oil Bible, I have put together two
different listings of motor oil comparisons. The same oils are listed, the order is simply different. One
lists the oils alphabetically, the same way as you will find in this printed version. However, there is a
second listing, which ranks the oils based upon a quality algorithm that I've set up.
Basically, I've used the viscosity index, pour point, flash point, high temperature/high shear and TBN
values for oils as the variables within the ranking algorithm. If these numbers are all provided and are
all good, the oil will rank high. The more of these values that are not provided or are poor, the lower the
ranking the oil will receive."
On page 151 of the PDF I've linked to above you can compare oil characteristics.