Okay, I'm new here, and I'm sure it's been asked hundreds of times, but I have a 2008 Mazda6 2.3l, and recently blew the motor at 113k miles. I cant seem to find a used motor with low miles on it unless it's around 300 miles away. What other years are compatible to go into my 08, if any at all?

 

Given how unreliable the 2.3 liter motors are turning out to be, here's a suggestion; search the internet for a discussion on the Ford Duratec 2.5 liter conversion. The two engines are externally 98% identical and the Ford is an easy swap; the good news is the 2.5 has some very important internal upgrades which make it A LOT MORE RELIABLE. Better still, the Ford mill is so plentiful folks are often finding used motors with low miles for under $400.

 

What do you regarding ECU's when swapping from 2.3 to 2.5ltr capacity?

Is the duratec 2.5 different to the older Mazda 2.5ltr engine?

 

As I understand it, you swap the block and head as a unit and then bolt on the Mazda manifolds and plumbing; no need to muck around with the ECU. As far as the pre-Skyactiv 2.5 goes, yes, as I understand it, the Ford Duratec and the older 2.5 are identical internally. What isn't so identical is the price of the used motors; the Mazda MZR 2.5 typically fetches well over $1,000 for a clean used motor, the Ford Duratec can often be had for $400 with less than 20,000 miles on the engine.