Engine Maintenance: Keeping Older Engines Running

I've already read quite a bit about what to do when you experience a loss of power. But is there a complete guide for engine parts that should be checked/replaced after a certain mileage because they can affect performance?

Sure, please provide the text you would like me to translate from German to English.

Fuel injectors.

How long do they typically last? When should they be replaced? How does wear and tear become noticeable? How do you test them? Which ones are suitable/recommended (based on engine type)?

Deposits in the engine.

How can you reliably get rid of them, and where can you find them?
Which products from "Liqui Moly + Co" are actually good, and which are not?

Who's talking about what?

"Regarding fuel injectors:"
=> Search function. This has been discussed many times before.

"Deposits" or "accumulations".
I replaced the head gasket and the oil pan gasket on my car at 150,000 km. I didn't find any deposits anywhere. If you always change the oil according to the manufacturer's recommendations and use good quality oil, there shouldn't be any problems.

You also read a lot of negative things about these oil flushes. On the one hand, it is said that dissolved deposits can clog narrow channels, and that engines that were already slightly leaky can then become significantly more leaky.

If you're asking about "older engines," I would prioritize the parts that are crucial for the engine's longevity, such as:

- Regularly check the timing belt and tensioner pulleys.
- For engines where this is a known issue, keep an eye on the crankshaft bolt, even if it has been worked on before.

The "nice-to-haves" would then be the less essential things, such as:

- Cleanliness of the intake area.
- Nozzles
- Spark plugs

Problems with the "Kür" usually become apparent well in advance.

Deposits in the engine.

How can you reliably get rid of them, and where can you find them?
Which products from 'Liqui Moly + Co' are actually good, and which are not?

Who is talking about what?

I've always been against adding any additives to engine oil, just like many others in this forum. I've also become more knowledgeable through my own experiences (not with my own car!).

Instead of using cheap motor oil, invest in good quality oil, stick to your recommended oil change intervals, and you'll never have to deal with any deposits!

You never know what kind of oil a used car has had or how often it has been changed. Therefore, it's best to immediately fill it with good quality oil (which already contains all the necessary additives and a good base oil) and change it again after approximately 5,000-8,000 kilometers. If there were any deposits present, they will slowly dissolve, be flushed out, and eventually end up in the filter.
When using 'flushing additives,' deposits are dissolved instantly (and not slowly!), and they travel through the oil lines in a clumpy form. Furthermore, weak and dried-out seals quickly become leaky. This will not do your car or your wallet any good!

You'll find a lot of information in this forum about important wear parts like timing belts, injectors, etc., and that information covers quite a few different engine models.

Best regards, Georg.