Hi JayCs
When we are monitoring worm drives, steel pinion, Bronze ring gear, we are correcting at an ISO 19/16, 20/16.
If you can run at an ISO 17/14-18/15 we would be looking hard to find enough significant debris to recommend an oil change,
Worm drives will operate with excess debris but because of the sliding motion transfering the energy three body wear is the most prevalent mode with two body adhesive wear commencing as the lubricant becomes heat damaged from the three body wear.
Steel pinion steel ring gear worm or spiral bevel drives are more sensitive to contamination and are best run @ an ISO 17/14, 18/15 maybe 19/15 with corrections required @ an ISO 19/16.
This is where we have to run to be reliable in Australia where the amount of hard inorganic crystalline particles can be 80-90 per 100 particles found in samples, non volcanic geographic areas where the amount of inorganic crystals are far less these ISO codes may go 1 ISO range higher.
Our advice will always be if the particle count is excessive in important oil lubricanted equipment, identify what the contaminate is by microscope and remove the source.
regards
Rob S
www.rttech.com.auHeat dmaged lubricant can increase the count without significant wear occuring
