[GC617289]

I read, with delight, the following website's evaluation of various oil change interval calculators:

http://neptune.spacebears.com/cars/stories/interval.html

Agreeing with the authors and using #5 (see comments at bottom of their page) I calculated the following intervals for my family's vehicles, all 2008 vintage:

Son's Mazdaspeed3 (manual): 7,800 miles (Pennzoil Ultra Euro 5W-40, TBN 10.4, 26mpg)
Wife's Honda Fit Sport (auto): 8,600 miles (Mobil 1 0W-30 AFE, TBN 9.1, 35mpg)
My Lexus IS-F: 14,700 miles (Mobil 1 0W-30 AFE, TBN 9.1, 22mpg)

If I were to switch to Pennzoil Ultra Euro 5W-40 the interval rises to >16,800 miles. Wow!

 

[GC617289]

There are three issues here that are always ignored:

1. Environmental: a large fraction of engine oil in the US disappears into the environment. Too-frequent oil changes are an important cause. Countries with aggressive environmental programs, such as Germany, have moved decisively to extend oil change intervals backed by well-supported research from the oil industry. For example, my brother in the UK has a 2009 BMW 335i and waited until his "oil change required" light came on at 18,400. His dealer said this was the correct approach.

2. Engineering: Modern synthetic oils/filters are capable of providing manufacturer-specified performance well beyond the "recommended" oil change interval over a wide range of ambient conditions.

3. Cultural: People often want tomorrow to be like yesterday and ignore progress. The oil industry has embraced a changed attitude to oil change intervals, mainly in other countries. The US lags well behind in this area.

Let's put the myth of frequent oil changes behind us, stop using false analogies such as "insurance", recognize that engine oil is very expensive, and drag ourselves into the 21st Century!