There is an abundance of misinformation and dis-information regarding the wide variety of synthetic lubricants on the market today, recommended oil drain intervals, and filter change intervals. The following information may add clarification.
Synthetic oils vary greatly in their manufacturers' recommended drain intervals from AMSOIL's 35,000 miles or one year for their "Series 2000" oils, to Pennzoil's 3,000 mile drain interval for their new synthetic oil.
There is only one way to determine a lubricant's remaining useful life: spectrochemical and physical OIL ANALYSIS. This inexpensive lab test will show whether of not the oil is suitable for continued use, and how it is currently performing in protecting the engine from wear. (concurrently the test will show the relative condition of the engine, emissions system, and oil and air filtration systems).
Like various synthetic oils, full-flow OIL FILTERS vary widely in type, filtration, and capacity, ranging from AMSOIL's and Hasting's top-line non-channeling "depth-media" filters, to FRAM's pleated paper surface filters. Top-line full-flow depth-media oil filters capture finer particles (10 microns) than pleated paper surface oil filters (40 microns) and have 30% greater holding capacity, and 35% longer life. Top-line oil filters, when used with a top-line synthetic oil like AMSOIL's Series 2000 lubricants, can effectively continue cleaning oil for 6-months or 15,000 miles. Again, oil analysis can verify whether or not the system is performing correctly.
Bypass "superfilters" can substantially extend the drain interval of top-line synthetic oil and associated oil filters. Top-line bypass oil filter systems can capture particles down to 1/10th micron, effectively cleaning the oil continuously as your drive your vehicle. Drain intervals in long-haul fleet trucks in excess of 400,000 miles are documented using the system above, verified with oil analysis.
Since 60% of engine wear comes from particles in the 5-20 micron range, selection of oil filters and their change interval is as critical to reducing engine wear as is the selection of synthetic oil and its drain interval.
Bottom line: Don't guess. Buy the best. Have it tested.
Will Miller
NOVA Engineering & Consulting
novaeng@tampabay.rr.com