Mkay.
Yes, so how did PD screw this up, exactly?
Because nobody in their right mind would put the old oil back in and then do an oil change. Even if they did, I'll ask this; on what 🤬 planet would old dirty oil give more HP then new clean oil?
Also, I'm confused on how you did an oil change after an engine rebuild. Are we playing the same game because after a rebuild it keeps telling me the oil does not need changed. The oil change is automatically part of the engine rebuild.
S2000 (US) '04 - 18481.8 miles (checked oil and was dirty, but did not change it beforehand)
Before rebuild - 229hp
After rebuild - 253hp
Now tells me oil does not need changed.
efini RX-7 Type RZ (FD) '95 - 15095.6 miles (checked oil and was dirty, but did not change it beforehand)
Before rebuild - 238hp
After rebuild - 264hp
Now tells me oil does not need changed.
Lets do it in different order now...
S2000 (US) '99 - 36719.3 miles
Before Oil Change or rebuild - 228hp
After Oil Change only - 239hp
After oil change then rebuild - 252hp
As we can clearly see,
my original estimation of 40hp was not that far off. Seeing as these cars with relatively low mileage saw an increase in the 20-30hp range.
Remember your original response?
Except a 210hp v6 won't be a 250hp v6 after an engine rebuild.