Porsche Repair: engine noise, vacuum leaks, fuel injector cleaner

Question
QUESTION: Hi, I have a 1989 porsche 944 with 128000 miles.  Sometimes it seems like i hear a slight knock or rattle in the motor, any idea what that could be caused by.  could it be cracked vacum lines or injectors. i got this oil called something purple, supposed to be real good stuff, and i just wanted to make shure the 15w40 the store gave me was the right weight. thanks alot

ANSWER: I don't think the Snake Oil is going fix the noise unless you down a few quarts of oil.

Where around the engine the noise coming from:
Front
Rear
Driver's side (LH)
Passg. side (RH)



---------- FOLLOW-UP ----------

QUESTION: It sounds like it was coming from the valve cover, and the oil i got was called royal purple. i put some fuel injector cleaner and some premium fuel. i hoping it just needs to be cleaned up.  the car seemed like the engine was just not well maintained the past couple years. i have receipts from 01 to 04 were the the engine had all new seals and valves grindes and all new belts.  it just seems like its a little sluggish.  with the oil i was just wondering if it was the right weight. when you give it gas it seems to bog a hair when you let off then it seems to steady back to about 7 to 9 thousand rpms

Answer
With regard to oil, you can either use what the owner's manual suggests, or see what fellow 944 owners like to use based on their opinions, such as found in a thread here:
http://forums.pelicanparts.com/showthread.php?t=398867&highlight=oil+weight

Personally I run a 20/50 non synthetic Castrol in the summer and something lighter in the winter.

With regard to the engine running problems there is a world of "things" to inspect, from spark to fuel and simple vacuum leaks; simply too much to cover here.

Yearly I usually drop in a bottle or two of Chevron's Techron fuel injector cleaner.  



Its time you started reading about the common problems and how to inspect, test and repair.  Here are three invaluable sites:

Pelicanparts.com
Rennlist.com
On the two above you can simply read or join and participate with fellow 944 owners, lots of fun.

And there is Clarks Garage, here:
http://www.clarks-garage.com/