On Fri, 26 Aug 2011 18:17:49 -0500, Steve Barker
wrote:

On 8/26/2011 11:57 AM, ed_h wrote:
On Aug 26, 10:53 am, Steve wrote:
On 8/24/2011 9:02 PM, Metspitzer wrote:

All the oil change places still put 3000 in the window sticker.

Good advice. Oil SHOULD be changed every 3000 miles.

--
Steve Barker
remove the "not" from my address to email

What is the source of this wisdom?


dirt. The basic design of the engine has not changed. Aluminum
bearings (basically) aluminum pistons, and cast iron crank and
cylinders. Oil gets dirty., doesn't matter how much the oil costs, or
how fancy the vehicle is. The oil still gets dirty in about 3000 miles.
(given an approximate 5 quart capacity). Larger sumps can go
proportionally longer.
There has been one MAJOR change in automotive engines/oil over tha
last 40+ years. And that tis the introduction of lead-free gasoline.
That is the only MAJOR change that has worked to make extended oil
change intervals viable, because with unleaded gasoline there needs to
be less Phosphorous and other additives to keep the lead from forming
harmfull deposits. This reduction has reduced theacid level in the
crankcase - allowing the buffer additives to last longer (which
allowed the oil companies to add less to the oil, getting you back,
basically, to pretty well the same point.

The other, lesser change, was the introduction of fuel injection,
which controls fuel mixture better and reduces fuel dilution of the
oil - which allows winter change intervals to more closely track warm
weather intervals.

For short trip, widely varying temperature and humidity conditions,
3000 mile 3 month oil change intervals still make some sense. These
conditions constitute "extreme" duty - as do trailer towing or
extended high speed high load operation. Aproxemaetly 30-50% of north
american driving falls outside of these parameters, making extended
oil drain periods acceptable.

My car generally drives 3-5 km at a time, 3 times a day, 5 days a
week, with an extra 15Km twice a day (one of those days)once a week
and an occaisional 100km drive every couple of weeks. Every couple of
years it gets a couple thousand KM put on over a 2 week period. 5000km
(3000 miles) is 5 months of winter driving, and 7 of warm weather
driving in a normal year.

My wife's car got about half as many trips of the same length per
week, and mabee twice as many 100km trips, with one 3000km trip over
the last 9 years. It's 16 years old and just turned the 160,000km
(100,000 miles) 2 weeks ago - for an average of 10,000km (6000 miles)
per year with 60% or more of those miles in the first 5 years, before
we bought it.

Is 2 oil changes a year per vehicle a waste of time, money, and other
resources??????

I think not.