Synthetics, Sludge and Moly contents.

[skyship]

I tend to be of a similar opinion to turbo picture newton, that there is not very much difference in how a fully synthetic oil and a good dino oil will perform unless you start pushing the oil change limits, BUT if you use a fully synthetic (Including HC synthetics) I think the chances of either sludge or varnish build up in the long term causing a problem for the turbo in particular are almost nil.
I am looking around to see if there is a better oil available in Germany than the LM Synthoil 5/40 and although I think Mobil 1 and Castrol Edge are just as good, does it help much in terms of cold start and multiple stop starts, to choose an oil with some Moly in it? Liqui Moly seem to have decided on using other anti wear additives in most of their oils.
Informed opinions would be good to read.

 

[Astro14]

On a turbo-diesel, I think your real issue is coking in the turbo bearings, generally caused by excessive bearing temperature. My MB 240D never had a hint of sludge, and it was run on a variety of oils, mostly CC and CD (what was available at the time), and when I would check valve clearance, the engine was covered in dirty, black oil, but a quick wipe with a rag revealed factory-new looking metal...all diesel rated oils are so much better now than then...I wouldn't really worry about sludge in a diesel...

My old Volvo 240 (intercooled, turbo 4 cylinder) ate the turbo at about 90,000 miles. Teardown showed heavy coking in the bearings. Ran it on Rotella or synthetic after that and never had another problem...of course, I upgraded to a water cooled bearing housing (it was only cooled by oil in the factory configuration)...but the point is: coking is more likely going to kill it, not sludge. There was no sludge in that engine at all...and since I was not the original owner, I can only assume that the first owner didn't let the turbo cool on each shutdown (critical if it only has the oil to cool it).