Hi,
Nickdfresh - Sludging of engines has been around almost forever! It is primarily a factor dominated by a few variables namely, engine breathing systems, lubricant quality, OCIs and application and etc. Excessive oil temperatures - even localised like in turbochargers for instance - is a major cause of rapid oxidation of inferior quality mineral lubricants - this can cause many problems
Sludging first became a real problem in Europe in the 1960s-1970s where the quality of the PCMOs didn't meet the engine's design needs. Some US engines of the 1950's were also prone to sludging with some lubricants - HDs lubricants (CAT Series 3 spec) always worked well in these
In the 1950s-1960s I quickly learned with BMC "A" and "B" Series engines and some US engines (in New Zealand) that the lubricant played a very real role in this end result - all other things being equal! This was confirmed later by my experiences in England and in Scandinavia over some years. It was the start of my love of HD (HDEO) lubricants in petrol engines. This was especially so in MB, VW and Porsche engines amongst many others including Studebaker Hawks etc etc.
This is a little less important today as PCMOs are of a much better quality and consistency between Brands - thanks largely due to ACEA (the API have been a "passenger" in this IMO over the years) and the ever increasing call for Manufacturer Approved and Listed lubricants
I cannot comment on the Toyota experience as it has not really been an issue here in OZ to my knowledge. The Toyotas in my "fleet" over the years (ranging from 1974 until the present) have all been deposit free even at very high mileages. Most (from 1979) have been fed a diet of synthetic lubricants right from their first OC. The use of a lessor lubricants than those specified is definately a reason for sludging as are OCIs that are too long and (perhaps) not monitored by UOAs. A general lack of basic maintenance amongst the general public confirms this
Serious sluging has persisted in diesel engines to this day where end users do not follow the engine maker's specifications for the lubricant and for OCIs required. I inspected a MB diesel engine last week that had failed for this very reason!
Experiences of oil starvation caused by sludging (or even perhaps by heavy varnishing) can stem from the oil pump's intake screen being much reduced in intake size (flow) by the deposits - either in bulk (sudden loss of OP - sludge) but usually by a gradual build up over time (varnish)
There is no doubt that some engine lubricants do keep engines much cleaner than others! I would always opt for the use of one of these - all other specifications being equal
What a long winded answer - sorry....................
Nickdfresh - Sludging of engines has been around almost forever! It is primarily a factor dominated by a few variables namely, engine breathing systems, lubricant quality, OCIs and application and etc. Excessive oil temperatures - even localised like in turbochargers for instance - is a major cause of rapid oxidation of inferior quality mineral lubricants - this can cause many problems
Sludging first became a real problem in Europe in the 1960s-1970s where the quality of the PCMOs didn't meet the engine's design needs. Some US engines of the 1950's were also prone to sludging with some lubricants - HDs lubricants (CAT Series 3 spec) always worked well in these
In the 1950s-1960s I quickly learned with BMC "A" and "B" Series engines and some US engines (in New Zealand) that the lubricant played a very real role in this end result - all other things being equal! This was confirmed later by my experiences in England and in Scandinavia over some years. It was the start of my love of HD (HDEO) lubricants in petrol engines. This was especially so in MB, VW and Porsche engines amongst many others including Studebaker Hawks etc etc.
This is a little less important today as PCMOs are of a much better quality and consistency between Brands - thanks largely due to ACEA (the API have been a "passenger" in this IMO over the years) and the ever increasing call for Manufacturer Approved and Listed lubricants
I cannot comment on the Toyota experience as it has not really been an issue here in OZ to my knowledge. The Toyotas in my "fleet" over the years (ranging from 1974 until the present) have all been deposit free even at very high mileages. Most (from 1979) have been fed a diet of synthetic lubricants right from their first OC. The use of a lessor lubricants than those specified is definately a reason for sludging as are OCIs that are too long and (perhaps) not monitored by UOAs. A general lack of basic maintenance amongst the general public confirms this
Serious sluging has persisted in diesel engines to this day where end users do not follow the engine maker's specifications for the lubricant and for OCIs required. I inspected a MB diesel engine last week that had failed for this very reason!
Experiences of oil starvation caused by sludging (or even perhaps by heavy varnishing) can stem from the oil pump's intake screen being much reduced in intake size (flow) by the deposits - either in bulk (sudden loss of OP - sludge) but usually by a gradual build up over time (varnish)
There is no doubt that some engine lubricants do keep engines much cleaner than others! I would always opt for the use of one of these - all other specifications being equal
What a long winded answer - sorry....................
