jzeeff,
Presumably most of these small engines use non-detergent oil? Particularly the splash lubed ones? Presumably you are not using these all the time?
Then they were designed that way and will run and last perfectly well as they are. Why not drain all the oil and filter it before returning it to the sumps.
While empty you can remove the sediment from each sump as the original documents instructed. If you are using detergent oil a lot of the contaminants will be kept in suspension. But also remember modern lubricants are/can be far(?) superior to those in the distant past.
If they are old engines they would have neeeded frequent oil changes due to chemical contamination of the oil using fuels of the day.
Remember also truck engines are much more highly stressed (specific BHP), have closer mechanical tolerances and pressure-lubed thin wall bearings. Different engine characteristics allltogether. Dustier conditions should be irrelevant. If dust gets into an engine it will play havoc with the internals. Air cleaners and sealed breathers are prerequisites for keeping dust out.
Your small portable engine oil filter might fit in a lunch box - I do not know how big your lunch box might be - but I doubt it.
Furthermore, checking magnetic sump plugs at regular intervals is a good way to note any abnormal or increased wear. Not changing the oil is going to miss that simple check.
I would add, too, that you gave no reference as to whether tha claim was by a user or by the supplier. If it was a supplier advertising their wares, I would be looking to se if it says 'up to' 50%. Reading needs quite a bit of interpretation at times.
My thoughts - follow the engine makers recommendations but take into account all the other factors which may have changed since those instructions were issued, but above all, do it right.
RAB
