Modern Engine sludging problems.

[dicer]

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.

 

[BrianPetersen]

Toyota had issues with certain V6 engines a few years ago.

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.

 

[PackardV8]

Those of us who were there in the day do not accept the proposition. Every day I tear down obsolete engines and getting them clean is the most difficult part of the rebuild. There is a sludge everywhere.

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

 

[Ticklemetech]

Agree with @Brianpetersen here. I've seen many vehicles gone to dust faster than they should have because of using cheap oil. Regular oil changes are a must for any vehicle.

 

[romke]

the fuel has changed and also has the return system of the blowby gases. together with the introduction of the direct injection type of Otto engines that has made it much more difficult to keep engines internally clean. part of the cleanliness of the valve stems was due to a detergent in the fuel, and since now the valvestems no longer cleaned by the fuel, the problems have got worse. also the composition of the blowby gases have changed which calls for more effective additives.

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.

 

[TrackRat]

The situation with major sludge that VW experienced a number of years ago in their 1.8L Turbo engines came primarily from people not using the proper engine oil as specified in the Owner's Manual. In severe situations even the specified partially synthetic oil would break down due to the severe heat from the turbo/engine operation. AFAIK since specifying a 100% synthetic oil that meets VW oil specifications for the specific engine model, no sludge issues have been experienced.

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.

https://www.audiusa.com/content/dam/audiusa/Documents/Audi-1997-2012-Technical-Service-Bulletin.pdf