From page six, one of his own links. It bears repeating.
Industry experts say modern engines are even more prone to sludge build up than older ones. So what’s the cause, and why is it making a comeback?
There are several key reasons.
Oil vapour and combustion gasses must be removed, usually by being channelled through the combustion process.
If these gasses are not disposed of efficiently, sludge will form. Some modern breather systems are more successful than others.
Changes to the positioning of the Catalytic Converter have led to changes in temperature, hot and cold spots, in and around the engine. Hot spots bake oil, cold spots cause acid and sludge.
Modern fuels produce much more acid when burnt. A proportion of this acidity enters the crankcase. Experts say that long term engine wear is now as likely to be down to acidity as friction.
Engines are no longer manufactured down to Thousandths but Microns. Tighter tolerances mean engines are
using less oil, and as a result customers fail to check levels and miss oil changes
Drivers who miss recommended oil changes are without doubt contributing to the problem. Lease vehicle drivers especially are quoted as being among the worst for neglecting DIY level checks.
Constant stop/start city driving accelerates sludge formation. Drivers who spend most of their time in urban traffi c should be advised to book oil change services more regularly.
If you do have a sludge prone engine, you should change the oil using the owners manual "severe service" guidelines.
If you want to run a PCMO 25,000 miles, do it. Just blame who you see in the mirror for any sludge or whatnot.