140k on F350 (DIY 'Vegistroke'-style conversion) and almost 90k on my Excursion (using V3 module from Frybrid, no longer available...). No issues related to WVO. F350 had a cracked piston/hole at 308k miles and got full engine rebuild - there was no indication of WVO in the combustion chamber, etc after 120k on the high-cholesterol diet.
A few key issues to prevent issues with using SVO/WVO:
- never start cold engine on VO. You want a HOT combustion chamber AND 160*+ VO. (IOW's - don't 'blend' VO/diesel)
- on the same note, do not allow ANY VO into the diesel tank (can't just use 6way 'Pollak' valves to select between VO and D2 tanks...)
- complete dewatering is prolly more important than filtering WVO for trouble-free operation
- use coolant - not electric heat - to heat VO. Electric heaters (vegtherm) tend to overheat the oil and cause polymerization (or worse, carbonized bits of WVO getting to injectors ain't good!!)
- The hotter the VO before the on-board VO filter, the longer yer filters will last in coooold weather
- Avoid WVO coming in contact with copper, carbon steel and to a lesser extent brass. Exposure to these metals expedite the polymerization process