From what I've read, the suggested oil change was 1000 miles or so way back in the 20's. Kendall oil started selling '2000 mile' oil in the late 20's. It wasn't until the 50's (don't quote me) that that figure was boosted to 3000 miles. Even then, the flat head motors, low temp engines, and crappy gas, it was pushing the limit.
By the time multi grade oil came out, l953, 3000 mile changes started showing up.
3000-3500 mile oil changes were the norm for a long time. The oil companies like it, the filter makers liked it, and the service stations and garages liked it. The myth persists even these days in some circles.
Most 'experts' say 5000 miles is a reasonable interval for most folks.
With the better engines, better oils, and hotter running engines (burns off acids and water contamination), most engines have a 7,500 mile suggested change. (normal duty).
With oil life monitors, some are finding 10-12,000 miles (mostly highway use) before the gizmos tell you to change oil.
Pick a reasonable interval that you're comfortable with and stick to it.
Synthetic oil can go a lot longer that conventional oil, and some higher end filters can go that long too.
Do some reading on O
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