It's a terrific engine, especially in a 94/95 E420. Later cars had plastic oil tubes that were a problem. From everything that I've heard and experienced the timing chains are bulletproof. Later cars had coil packs rather than distributor cap/rotor but it's not a big deal. Caps/rotors, 2 each, are about $200, maybe every 50k to 75k. I've heard of no top end problems and there's just no telling how long the bottom ends will last. It's not as easy to work on as a 300E but an overall incredible engine. It's one of the last things that Mercedes built to a standard rather than a price.