If there's been some updated analysis recently, I've not seen it. But my concern would be the different outcomes needed for air-cooled bikes made in the 60s thru the 80s/90s (/2 and Airhead eras) versus what a water-cooled car needs that was manufactured since 2000 and which undergoes relatively frequent overhauls (if raced). Racers need to reduce frictional losses...not something we're that concerned about on our bikes.
I've read through the focused discussions starting with what Paul Glaves announced in the June 1999 ON about BMWs service bulletins at the time API ratings were changing from SG/SH to SJ and cautioned against their use (possibly a warranty issue). SJ oils dropped the ZDDP content (to no more than 1000 ppm) in favor or less harm on catalytic converters but the bulletins seemed to indicate that if the bottle indicated continued adherence to SG/SH, it might be OK to use. I can't see how you can meet SJ but still have the higher ZDDP levels (typically >1200 ppm) in SG/SH. Jeff DiCarlo followed up this with his analysis in October 1999. That article is on the IBMWR webste:
http://www.ibmwr.org/otech/oilreport.html
I have also read the four updates done by Matt Parkhouse that first showed up in 2002 and the last was in 2009 (two articles that year).
My next door neighbor is an AMS oil independent distributor and I got a hard copy of a pamphlet ("A Study of Motorcycle Oils", second edition, June 2009) which is on the web if you google it. As you can imagine, AMS oil comes out with top honors but the pamphlet does describe a whole range of tests that were performed...some which we could repeat.
My thought was to update the analyses that had already been done in order to see what oils have changed formulation and to investigate new oils that are now offered. All of the ON analyses have been limited to anti-wear (ZDDP) and anti-corrosion (Ca/Mg etc.) These tests are somewhat easy to do using a spectrograph process measuring the oil vapors when they are hit with an arc.
The AMS oil pamphlet has other tests that I would like to see but are probably very costly:
- viscosity grade -- where does an oil stand in the spec range for a 40w or 50w oil
- wear indicator (4-ball) -- measures the oils ability to minimize wear in metal-to-metal contact. Unfortunately, it appears that there's no direct relationship between zinc levels and minimizing wear.
- volatiliy -- how much of the additive package burns off over time
- acid neutralization -- this helps prevent internal damage over time due to build of acids. This seems like it might be good for bikes that are not ridden that often or stored in winter. It is a strong point for synthetics which is part of why they suggest longer drain intervals when using synthetics.
These tests would require substantial time and money. I plan to discuss some of this with co-workers and get some recommendations for important tests.
Then the hard part will be to get a selection of oils to test. To some degree we should draw from past tests to monitor if there's been any changes. But at the same time, there are many "favorite" oils with varying prices, some you have to buy over the web, some you can get at the local store. I'd want to focus on oils that are labeled SG/SH as well as demonstrate differences in protection if you go beyond this rating.