I had full lab facilities available to me at a used oil recycling facility. We ran long term (10 year, 250,000 km) oil tests on 2 similar-driven identical 2003 Honda Accords with recommended 10k mile oil changes. Results were a little surprising in that one of the Accords had oil changed at 5,000 miles and registered higher engine wear. One possibility was that the high level of additives in new oil may have been led to higher wear. This anomaly was verified in subsequent tests ie a higher level of engine wear is indicated shortly after fresh oil is added.
With synthetics in the Accords, the OCI could have been extended: less wear evident. Both Accords were switched to synthetics in 2010 but OCI was not changed.
With motorcycles because our transmissions chew the oil more than cars, oil has a tendency to shear at a quicker rate than a car so that becomes more of a factor than contaminant or additive loss. In any case I have rarely seen an engine fail when properly maintained.
I read hundreds of UOA reports and am shocked by how frequently some people change their oil. My guess is anyone who will pay for UOA is likely skewed toward frequent changes.
So my 1995 VT1100C2 gets its oil changed at recommended intervals of 8,000 miles or each year. I only have about 70k km because I have other bikes. however my GL has 350,000 km and no issues with once a year oil changes. I changed to T6 a few years ago because the viscosity, additive package and shear stability, however I remain with the recommended OCI. My tests indicate that motor may exist another 22 years, however I ....
Last edited by gdb069; 03-19-2017 at 10:42 AM.