I have a 2006 Lincoln Navigator and I just changed the oil. I recently noticed a light rattle or knocking noise as I begin to accelerate but it goes away. It kind of sounds like my oil pan is empty, but I checked my oil level and it looks normal. I used 7 quarts of 5w-20 as recommended and replaced the oil filter. Is this normal or the beginning of a bigger problem? I have about 93,000 miles on the truck and none of the sensor lights are on.

 

You hear the noise when the engine is cold, warm, or hot?

 

When warm and hot but not cold.

 

Then you could be looking at a rod bearing that's about to fail.

 

Is that common? How much does that normally run to repair? I just bought the truck in May.

 

Common...no, but the likelihood of it failing all depends on how the truck was maintained before you bought it.

 

I just spoke with someone else and they said that even though I used the recommended oil (5w-20), for my recent oil change, the oil is too thin and that's why I here the light rattling. He suggested using 20-50 since I have over 90,000 miles on it. Your thoughts?

 

I also had not heard the rattling until I changed my oil. He said that the previous owner must have used thicker oil. And just to add the truck was kept in impeccable condition when I bought it with a clean Carfax report.

 

I don't know about 20-50 but it will take forever to warm up in the cold, I bet the previous owner used heavy oil or added a bottle of lucas.

 

20-50 is way too heavy for these engines, with the VCT system and all. I'd try 5-30 or perhaps 10-30 depending on the temperature where you are, and max 10-40 if the rattling is still there. Any more than that and the oil will be too thick to properly operate the variable cam timing phasers.

 

Also, make sure you use the correct Motorcraft oil filter with these engines. It has a check valve inside which is important for these engines, which generic aftermarket filters often lacks.

 

I have 145K on mine and run 5W-20 Motorcraft synthetic blend without any noises. IMO, running the thicker oil masks a problem that will eventually get worse. The previous owner might have run a thicker oil to cover the noise long enough to sell the truck to some unsuspecting person.

 

It depends on where you live, and I believe that in Europe Ford actually recommends 5-30 or something like that in a TSB. Locally here, they recommend 5-30 or 10-30, but that is due to the tropical climate, it's always hot here.

 

20-50 is way to thick for a normal motor , 10-30 is fine i wouldnt run 5-30 even if it was free . if its knocking , my guess is a rod , and cost all deppends on the damage its done to the crank . drop the oil pan and check the rod caps for play if u are wrench savy parts for a bearing are not to bad , crank is 4 bills