Quote"...The 1.3L in this car probably had the factory fill in for 50,000 miles, and probably didn't even start making sludge out of it till ~25-30k. From what I have read, these engines are easy on oil, and nobody had ever heard of one with sludge until mine comes along, suggesting that even with really poor oil change practices, these engines would ordinarily stay clean...."
Yes, while these engines are quite easy on oil, one shouldn't neglect (still) proper OCIs. 50,000miles per oil change? That's nuts! I wouldn't go past 6,000miles (or 8,000kms) OCI if I use factory fill/bulk dino or similar.
Suzuki engines are typically reliable unless you neglect OCI, thermostat failure and PCV clogging (their PCV venting/metering is a bit "archaic" by design).
IMHO at this stage the damage is somewhat done. Unless you sacrifice some serious elbow grease to rid of it, IMHO it will take another 200,000kms or more of regular OCI, additive changes, etc. to dissolve most of the visible deposits.