Chris Mouw

Hi, everybody. I have a 2004 Audi A6 2.7t. I have not had any issues with my car until I changed the oil in it for the first time. I put 0w 40 mobile 1 full synthetic in it. I put 6 quarts in it and started the engine to get all the fluid circulated and shut the engine down after about 30 to 45 seconds. I then put the rest of the .9 quarts or so in to top it off. I started it up again and took it around the block and I now here a knocking sound from the engine. It does not sound like metal hitting metal. But it deffinately wasn't there before. My question is, could this be because of the oil being too light and I need to go up to a 5W 40 or could I have damaged my engine some how?

N_Jay

Knocking is never good.
Any issues before you changed the oil?
Any error lights on your test drive.

Chris Mouw

I had zero issues during my test drive. I had been driving the car for about five months now and had no inclination of any knocking. I am starting to wonder if the previous owner had put some lucus in it to cover up the knock sound and then sold the problem to me. I hate to get rid of it now. Either way I am loosing money on it. I'm thinking about looking for a used engine now.

N_Jay

This was your first change?

might be worth getting the oil analyzed, or just add a can of motor honey and sell it.

redbullgotwings

i like it, lol. That may be the way to go. Order a mechanic stethoscope and see if the knock is from the bottom end of the motor or somewhere else.

my flywheel just started to tick recently and i thought that was the lower end too but its not.

the bottom end of these motors are rugged, i beat the sh*t out of mine and it has 260k on it and its still runs great.

redbullgotwings

but not its not the oil, 0-40 is all you can run in this car. anything else will throw codes.

Chris Mouw

The knocking sound that it was making actually seems to have quieted down a lot. I almost don't here it anymore. It did seem to sound like it was coming from the bottom end. I'm just guessing though, because I haven't used a stethoscope. I bet the guy who had it before me had thicker oil in it, and that is why it seemed so quiet. With the correct oil in it I can now here the rotating assembly doing what it does. I now have almost a 140,000 miles on this car, and with it being my first European car and not knowing much about it I tend to p*ssy foot it around.

johnkk

Thicker oil will not throw codes. But a heavy dose of STP or similar may cover up some knocking noises.

5w40 is also specified, and IMO, preferred. 10w40 or even 15w50(summer) would be OK as long as it's synthetic.

If it's a crank or connecting rod bearing knock, you're in for a new engine. You might have a valve train knock that is due to worn out cam chain tensioner guides, which is diy if you are handy. Could also be a cam follower/lifter that is stuck. The synthetic oil might dissolve the crud. The cam and valve noises are more of a clatter than a clunk/knock that you get from shot bearings.

Chris Mouw

The noise I'm getting is more of a low pitch sounding knock or tick. I only here it during the rev. As soon as I start to idle or the rpm's level off at just say 2500 rpm's the knock or tick goes away. I think I'll change the oil and put 5w 40 in instead. I think it'll be better for the engine.

tenspeed

Sorry to say but that sounds like rod knock to me. The previous owner added a viscosity builder to the sump to hide the noise.

Have it checked out. It's hard to determine just from a internet description. Run a compression check. Send in a oil sample. Find out if and what is broken so you know what direction to take.