u/JBL9889

I have a 2009 Mercury Grand Marquis LS 4.6L V8 with about 300,000 km (186k miles).

Sometimes I hear a diesel-like rattling noise when accelerating, mostly under hard acceleration but occasionally with light acceleration too.

The weird part is that the noise doesn't happen when revving the engine while stationary. The car runs strong, no misfires or rough idle.

It also uses about 1 liter of oil every 4,000 km, and I found some oil residue around the sides and underneath the engine, but no obvious puddles.

What could cause this noise? Knock/detonation, timing components, exhaust/heat shield, or something else?

I have a 2009 Mercury Grand Marquis 4.6 V8 with about 300,000 km (186k miles). It uses around 1 liter every 4,000 km (2,500 miles).

There are no obvious leaks or blue smoke, and the engine runs well. I take very good care of the car and change the oil on time.

I saw someone with the same 4.6 V8 at 400,000 km (249k miles) who also changes the oil every 4,000 km but says he doesn't use any oil between changes.

Why would mine use oil despite having 100k fewer km and being well maintained? Is this normal variation between engines, or could it point to valve stem seals, piston rings, PCV, or something else?

Hello everyone,

I have a 2009 Mercury Grand Marquis with the 4.6L V8 engine. The car has around 300,000 km on it.

The transmission is currently working very well:

• Shifts are smooth.
• No slipping.
• No hard shifts.
• No delay when shifting from Park to Drive or Reverse.
• It engages immediately.

I checked the transmission fluid recently. The fluid color is dark brown to almost black, and there is a noticeable smell. A shop checked it and said the fluid condition is around 20% and recommended a transmission flush with cleaning chemicals to clean the entire transmission system.

I am worried because I have heard stories about high-mileage transmissions failing after a flush. Since my transmission is still shifting perfectly, would you recommend:

1. A full flush with cleaning chemicals?
2. Or just dropping the pan, changing the filter, replacing the gasket, and refilling with Mercon V fluid?

I want to protect the transmission and avoid causing problems.

What would you do in my situation?

i have my grand marquis 2009 with 186kmile it burns about half every 1553.428mile

no leak , no smoke engine in good shape what cause the porblem i use 20w50 castrol cuz weather here is so hot

I have a Mercury grand marquis 2009 with 298,000 km on it. The AC has a problem: it doesn’t cool unless I pour water on the ecu /module. I changed the sensors related to the computer ecu and it started cooling normally again, but replacing those sensors cost me a lot of money. How can I insulate the computer/module from the heat of the sun and the car sry for bad english