I have a hundae enterage and it's a 2007 with 41,000 miles. Car was shaking and sputtering and nearly stalling at stop. Brought it to shop and was told the whole engine needs to be replaced. Said that because oil changes were not done every 3,000 miles that that engine was damaged. I can't believe that's the only solution.

Yes, check out Auto-RX online. It's an ester-based product that will clean up serious sludging problems in engines and transmissions. Well-regarded product.

Afterwards, start using full-synthetic engine oil, changing the oil and filter every 6,000 miles or 6 months, whichever comes first.

You can try engine cleaner, you put it in before an oil change. If you are a home mechanic, you might want to consider a valve job and cleaning the cylinder head and pistons yourself. I wouldn't believe your mechanic. Check your spark plugs, wires and also check your air filter. Is your check engine light on? The problem you described also may sound like a bad Mass airflow sensor. What part of the engine did the mechanic say was damaged?

It has saved many engines. Just make sure you have a sludging problem and not something else. Auto-RX will safely clean the engine, unlike many other products.