On Wed, 31 Aug 2011 13:57:35 -0700, sms88
wrote:

On 8/31/2011 1:44 PM, wrote:
On Wed, 31 Aug 2011 13:18:24 -0700,
wrote:

On 8/30/2011 8:10 PM, Steve Barker wrote:
On 8/30/2011 9:09 PM, ed_h wrote:

Ignore your owner's manual at your peril. You're wrong.

Many owner's manuals, including mine, don't include the definition of
severe service. They say to change the oil when the engine oil
monitor says to, or 7500 miles, whichever comes first. The later is
apparently to cover the possibility of a failed monitor.

For my rather typical driving, which often includes some of the items
on the severe service list, my monitor tells me to change oil at
around 7000 miles.

"The List" is hard to apply to a specific car and driver.
Intentionally, maybe.

I'd like to see the manual that doesn't have a sever recommendation.

New Toyotas sold in the U.S.. Toyota may have over-reacted, but they
believed that there were too many people that qualified for severe
service (5000 miles) that were following the normal service (7500
miles), so they went to 5000 miles period. This may change as they fit
newer models with oil monitoring systems, since the result has been many
people changing their oil far more often than necessary.

In YOUR opinion.

No, it's not my opinion. When the whole sludge thing happened Toyota
stated that it was the result of drivers that should have followed the
severe service oil change interval (5000 miles) following the normal oil
change interval (7500 miles). They thought it too confusing to have the
two service schedules so they rolled everything back to 5000 miles.

If the extra oil changes eliminate the sludge/coke
failures, they are NOT being changed far more often than "necessary"

No argument there. But it's still a far cry from the days of lower
quality oils when 3000 miles was the norm.
Like I said before - it's NOT better oils - it's less agressive
fuels and better mixture control - which allows what ammounts to a
POORER oil to do an adequate job. To be more accurate, a slightly
DIFFERENT oil - better in some ways, inferior in others.