Noisy Engine From E240

I bought E240 Mercedes (year 2000) when new. It's mileage now is 55,000km. It is always serviced and the engine oil used is fully synthetic 5W-40. After four years, the engine became noisy (similar to noisy teppettes). The problem started after an engine oil change at workshop (fully sythetic oil 5W-40 was used).

I was later advised to drain the engine oil after only 1000km, and this time I used Revenol 5W-40 as replacement. But the noisy engine still persists. The mechanic used an approved additive to lubricate the teppettes, but it did not help. After just 3000km using the changed oil, I was reminded to check the oil levels. I had to add two litres of Revenol 5W-40 to bring the oil level to normal.

Now, my mechanic want to open the engine to check the problem. I am skeptical, as the car has only done 50,000km. I am also worried about the sudden increase in engine oil consumption after just 3,000km.

Reply:
I hate to say this. As you did not mention the brand of synthetic oil used, can I assumed it is something that the workshop recommended and is not one of the major brands? If that the case, one really does not know the quality of the oil, even if it was suitable for your car. There is this allusion that synthetic oils must be used for modern engines, and asa result there are all kinds of oils being sold that claim to be synthetic or semi synthetic.

I fear there is damage to your valve train and even the pistons and rings because at 55k, your car should not be consuming oil. You mentioned using Revenol 5W-40, but I couldn't find such a brand anywhere. You may need to open the engine as it appears that the oils you have been using have caused quite a lot of wear.

In future you should use well-known brand. Petronas, for instance, has a comprehensive range of synthetic lubricants under the Synthium brand.