Originally Posted by Jerry Bransford
The 3K mile oil change interval is nothing more than something pushed by the quick change oil outfits like Jiffylube. Unless you are in constantly harsh dusty conditions, I'd use 5K to even 7.5K change intervals. Personally, I change my engine oil every 5K miles unless I was wheeling in extra-dusty conditions.
We use 3K intervals for our ambulances at the county. They see that milage in about 3-4 weeks. I was looking at my owners manual and it says to use 7500 mile intervals for oil changes under normal operating conditions. It says to use 3K intervals if any of the following apply to you regularly:
day or night temps below freezing
Stop and go driving
Extensive engine idling conditions
Driving in dusty conditions
Short trips of less than 10 miles
More than 50% of your driving is at sustained high speeds during hot weather above 90 degress F
Taxi, Police, or delivery service
Off-road or desert driving
If equipped for and operating with E-85 fuel
I use a compromise and I go with 5K intervals all the time. That's just me. Hope this helps.