Engine oil additive/cleaner

[zaku]

I've been told by the mechanic at the garage that I should add an oil "cleaner" to the engine to clean up when the engine reaches a certain mileage. He showed me something, i don't remember which brand but it costs like $60 for a little bottle. I didn't took it as I was thinking it might cost cheaper if I find it somewhere else by myself.
Do you guy know if this engine oil additive actually works? If so, which one should I buy and where?

Thanks.

 

[reno2486]

I ordered the roof cleaner on monday and was happy to see it arrived 2 days later on Wed afternoon. The package contained the cleaner, my invoice, and detailed instructions. Over the weekend John put the cleaner on (he was skeptical about it working). When he finished cleaning both of us were shocked at how well it worked
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2013 MERCEDES BENZ SL-CLASS