Mark72 is right.
Mark72 is wrong.
Actually, it's a bit of both.
Equipment longevity comes from proper maintenance plans, not some hyper-sensitive selection of lubricant.
There are two means to the same end. If you want your equipment to last (engine, trany, diffs, xfer case, gearbox, etc) then you must develop and follow a good maintenance plan.
There are plenty of living examples of vehicles with high mileage by using synthetic fluids, bypass filtration, and extended OCIs. These vehicles are very reliable and can last, conceivably, forever.
(warning - these are "testimonials" and not hard data, but the point is that you can read about many customers that do extended OCIs with this product line, although those experiences are NOT UNIQUE to this product line).
http://www.fs2500filter.com/testimonials.htm
The same can be said for vehicles that OCI often. Here are two examples:
http://www.autoblog.com/2008/02/01/wisconsin-mans-91-silverado-set-to-hit-1-million-miles/
http://www.knfilters.com/news/news.aspx?ID=157
What everyone seems to get caught up in, is that they think there is only one solution to longevity. UNTRUE! You have two choices.
1) frequent OCIs (typically done with decent, but low cost, fluids)
2) extended OCIs (typically done with high-end, expensive, synthetics and/or often bypass filtration)
Extended OCIs are NOT about making equipment last longer. Extended OCIs are about making the FLUID last longer. Extended OCIs (and the products that get them there) are fiscal savings tools for situations where large/long annual driving patterns can reap the benefit of fewer oil changes with less purchased products, services and downtime.
Since a great many of us don't drive enough to warrant extended OCIs as a savings tool, we can do just fine by using short OCIs.
The bottom line is that equipment longevity comes from clean lubricants. Clean lubricants are a function of your maintenance plan. You maintenance plan should be based upon a multitude of things including:
annual mileage
tolerance for maintenance downtime
availability of products/services
environmental concerns and conditions
operating concerns and conditions
cost of products and services
etc
1) you can flush out the contaminants with frequent OCIs
2) you can filter out the contaminants for longer OCIs
Two roads to the same destination. The only difference is the cost of getting there, and that is UNIQUE to each individual situation. There is no "best" maintenance plan for every person or situation, any more than there is a "best" oil, "best" oil filter, "best" toothbrush, "best" kitchen knife, etc.
Nearly all people get product selection backwards. They buy a product based upon rhetoric, hype, hearsay, marketing, mythology, etc, and then try to cram it into their operating/maintenace plan. The REAL way to gain success is to analyze your use, and then select a program and plan that fits your own individual needs. Pair up your products with your maintenance program, and you'll have success.
Thus endeth the lesson.
