Modern Engine sludging problems.
Modern Engine sludging problems.
(OP)
With the advent of full synthetic motor oils why is it such an issue. Is there anyone here that has dealt with any sort of study of this problem, in any of the large auto manufactures labs? I've seen various photo's and articles on the net that show some problems with sludge that even the old Stovebolts didn't have and they were some times very dirty and sludgy inside.





RE: Modern Engine sludging problems.
I don't think the problem is with synthetic oils ... I think the problem is with people using the cheapest oil they can find, using the car for short trips ("severe service"), and leaving the oil in there too long.
RE: Modern Engine sludging problems.
Next door is my machinist who rebuilds modern engines. Most are so clean inside, they could go without a wash. The bores are unworn.
jack vines
RE: Modern Engine sludging problems.
RE: Modern Engine sludging problems.
another influence is the drive pattern: there is a tendency of making more short trips and less longer ones where engines reach their optimal temperature.
with modern high quality oils it need not be a problem, but those are not always used.
RE: Modern Engine sludging problems.
Quality modern engine oils in general are superior to older Dino based oils. Unfortunately there are many modern oils that meet some industry specification but they don't meet the needs on many specific engine requirements. All pass car makers that I know of specify what oil and viscosity must be used for a given engine and those specifications are usually very important. You can have oils that are wonderful in one engine model but lacking for a different engine application. In many cases failing to use the specified oil can lead to increased engine wear and in some extreme cases engine failure.
Modern oils lack "ZDDP"- (zinc diakyl-dithiophosphate which is an anti-wear additive used in older engine oils and required specifically for flat tappet camshafts to prevent excessive wear. Since the EPA decided to remove zinc from modern engine oils you need to buy oils that specifically have this additive or buy the additive and add it to oils for use in older flat tappet engines to prevent excessive camshaft lobe wear.
It's worth noting that most Euro car makers have specific engine oil specifications for each series of engines based on lab and real world testing. As an example the VW Pump Duse Diesel engines have individual cyl. injection pumps that are camshaft driven and inject at a pressure of ~10,000 PSI. The design imposes such high cam lobe pressure as to require a VW 501 01 oil only or the warranty is voided and the cam lobes will be extremely worn in a short period of time.
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