philthehill wrote: ↑Fri Mar 15, 2024 10:41 pm
Better to have the sludge in the oil filter rather than in the rest of the engine.
When I worked in the garage trade we looked after a high annual mileage petrol Hillman Hunter. The engine was filled with diesel engine oil and it was surprising how clean the engine internals were when it was stripped for overhaul.
No sludge was found in any part of the engine and very little component wear experienced either.
That is interesting. The oil filters are cheap and I certainly would not mind changing the filter more often. Not much oil is lost doing a filter.
Stephen
1969 1098cc Convertible “Xavier” which I have owned since 1989.
Just for info. ‘Sludge’ is not particularly abrasive. It is so fine (particle size) that it will mostly go through filters. It flocculates and settles out slowly, possibly sticking to some rotary moving parts. Those agglomerated lumps would be the nuisance and oil pumps can pass filterable sized particles to the filter element (and block it, eventually).
Detergent oils carry the ‘sludge’ in suspension for the service life-time between oil changes. The sludge doesn’t agglomerate, due to the detergent action and is normally removed at service intervals.
Engines (apart from dry sump types) run on non-detergent oils will have some sludge deposits in the engine . Changing to detergent oils without care (usually including some dismantling) can sometimes prove disastrous for the engine.
I have one engine (I changed it to detergent lubrication) which suffered a blocked oil feed to the governor housing. I had removed as much sludge as I could, when returning the engine to working order, but still it blocked a small diameter line to the governor. I found it and avoided the governor housing dismantling itself (I still have parts of the original housing, which had previously exploded due to wear of pins retaining the governor weights). The other slightly risky possibilities were the rifle drillings through the con rods for small-end lubrication - but they have been OK. Generally, any agglomerated particles would perhaps/hopefully be ‘chopped up’ by the gear oil pump but something got through. Big-end bearing clearance would have made it very unlikely that any large lumps would find the con rod drillings. The engine did not have full-flow oil filtration.
It was never a practical option to completely dismantle that engine. On other similar engines the timing gears have collected a coating of ‘sludge’ over many years of operation. Many stationary engines, with splash feed for the crank bearings, have had only the dipper track clear of sludge.
I run all my engines on detergent oils. Universal agri oils served me well except for the Peugeot 607, which had its specified low-ash lube to protect the DPF.installation
