Sludge Monster, Easy on Oil, Dirty Engine, Clean Engine

[Donald]

I think it's somewhat subjective also.

But there have been a few engines over the years from good auto brands that just got more sludge than one would expect. Probably a design issue with areas of the head getting hotter than they should.

But there are things one can do to help the engine lubrication such as reasonable oil OCI, easy on the gas pedal while engine is warming up, synthetic oil, no oil from Dollar Store, keep eye on oil level, no overheating, not many short trips.

 

[Bill7]

These are terms we sometimes hear when describing an engine. What engineering or design characteristics cause an engine to be hard on oil, easy on oil, dirty, clean, sludge monster, etc.

Engines which are hard on oil:
Extreme heat in certain parts of the engine (VCM, turbos)
Extreme heat caused by poorly designed PCV systems (Honda Odysseys, Toyota's from late 1990's / early 2000's).
Fuel dilution causing engine oil to thin below grade (Direct Injection engines)
Stop/Start technology (Ex: Ford Ecoboost)

Shorter OCI and using thicker synthetic oil handle the extreme heat better.

 

[Number_35]

It depends on the engine. Some MB engines need to have the timing chain/s replaced every 100k miles. I've driven bimmers since 1974 and never had a timing chain problem. However, my 1985 BMW 325e had a timing belt which was religiously replaced every 4 years as it was an interference engine. My BIL's Subie had 200k miles on the clock before the timing belt broken. There was no damage as the engine wasn't an interference engine.

Timing belts vs. chains is a whole other discussion, with the merits and demerits of both discussed here on BITOG in depth.

But w.r.t. oil life, I think a belt is better.

 

[Bill7]

Timing belts vs. chains is a whole other discussion, with the merits and demerits of both discussed here on BITOG in depth.

But w.r.t. oil life, I think a belt is better.

Agreed. Timing chains put extra stress on the oil. Several manufactures have had wear issues with timing chains.
I prefer timing belts. Replacement at 110k miles for me with OEM parts purchased from the lowest priced online dealership parts depts and having my local mechanic install has averaged $800 total which isn't too bad.

 

[Number_35]

Agreed. Timing chains put extra stress on the oil. Several manufactures have had wear issues with timing chains.
I prefer timing belts. Replacement at 110k miles for me with OEM parts purchased from the lowest priced online dealership parts depts and having my local mechanic install has averaged $800 total which isn't too bad.

Agreed - because the belts are designed to be changed, a timing belt replacement tends to be easier than a timing chain.

I don't have a vehicle with a belt at present, but believe my cars in the past with timing belts all had non-interference engines.