If this is a freshly rebuilt engine, I would change it now to get all the metal junk out of it. I'd do the same in 3000 miles then you can extend the change time. When I break in a freshly rebuilt engine, I change the oil (cheap oil) at 500, 1000, 3000 then whenever the interval should be. The best way to figure it is after you change oil at 3000, send it for an analysis. My 99 E300 has it's own crude meter and sometimes, based on the driving I do, I can go 13000 miles before a change. Sometimes 8000.

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01 Ford Excursion Powerstroke
99 E300 Turbodiesel
91 Vette with 383 motor
05 Polaris Sportsman 800 EFI
06 Polaris Sportsman 500 EFI
03 SeaDoo GTX SC Red
03 SeaDoo GTX SC Yellow
04 Tailgator 21 ft Toy Hauler
11 Harley Davidson 883 SuperLow