Extended Oil Change Interval

It is pretty variable, anything over the manufacturer recommended oil change interval can be considered extended. By how much over that interval is dependent on the condition of the car, how it is driven, ambient conditions, type of oil used, filtration ability, if makeup oil is used, etc.

In some extreme cases, even the manufacturer recommended oil change might be too long, that point have to run on a severe operations oil change schedule. On the other side of the spectrum, with a well maintained engine, right oil, right filtration - 12K to 25K miles between oil changes is possible.

If you want to run extended oil changes - to be safe, you must do UOA. This is one of those things that you cannot "guess" on. Some owners might get lucky with blindly extended their change interval, unfortunately, that is not always typical. Each engine is different, each driver is different - there is no" set" mileage that is right for every case.

Short answer yes - anything more than the recommended oil change interval can be considered "extended".

According to Toyota (now) - any oil change greater than 5000 miles is considered an extended oil change interval. According to the petroleum industry - anything above 3000 miles is considered extended intervals. According to some owners at BITOG, they don't consider anything under 10K miles as extended.

As previously, most people consider anything over the manufacturer recommended oil change interval to be an extended oil change interval. But there really isn't a well defined, hard number or percentage that says, if you go "---" distance further, then you in the extended oil change interval regime. Extended oil change is still a "fuzzy" concept to some.

This is important for some cases, as technically, if you "extend" an oil change interval under the vehicle's warranty period and you suffer an oil related failure, you could be denied warranty coverage.

To me, extending the oil change interval is pretty safe, oil tech and ease of testing gives you a pretty clear picture of what the oil is doing in the engine. But you always have to keep in mind that if anything happens to the car, that is all on you. I go into this knowing that I know exactly how far the oil can protect me, from periodic UOAs, and i know that anything could happen (formulation changes with motor oils, variability with blends at the refinery) - so it my engine blows up, I own up to it and I'll deal with it when that time comes.