I've gotten a little over 500 miles on the rebuilt EJ25, and I'm starting to wonder when I should do the first oil change. I filled it with Royal Purple special break in oil, I've been trying not to run at any one RPM for very long, doing all the usual break in routine.

Should I change it out soon? or maybe just swap out the filter and keep using that fancy, expensive oil a couple thousand more miles?  There's very little carbon showing in the oil, so I suspect the rings are seating nicely.

 

Get onto the manufacturer for the best instruction. I was of the understanding that break-in oil was not to be driven on, just start up, idling, tuning etc. I have never used it, just used the grade that was for the engine and change it and filter at 600 miles

How many hours would you run the break in oil? For my loader, the recommendation was 50 hours above 50% load, which would be roughly 1000 highway miles on a car.

"Get on to the manufacturer" was a good suggestion. Here's what RP says:

Quote

We recommend using our Engine Break-In Oil for a minimum of 500-1,000 miles in street driven gasoline engines to assure that the complete ring break-in has been completed before switching to one of our full synthetic engine oils. If need be, you can use for up to 2500 miles.

 

I don't use specially formulated "break-in" oils. Just the conventional version of what I'll run normally after break-in. 500-1000 miles before changing to anything synthetic should be sufficient. Sometimes I drain the oil at 250 miles or so just to have a look at it and if nothing scary is seen, I'll pour it back in the engine (filtering through a very fine mesh screen) and run another 500 miles on it before the first drain and refill with the oil I plan to use long-term.

The first oil change is to flush out and machining swarf and loose particles.  Put in conventional oil now, cut open the filter and inspect oil.  It's an EJ25 with standard rings and metal headgasket, after the first oil change and you don't find unusual glitter, just drive it hard and get the seating over with.  Get it warm, accelerate harder than usual, use lots of engine braking in between.