Clicking Noise in C5

Uhhh, so many possibilities.

Is it irregular or rhythmic?

How quickly does the click occur?

Is the frequency of the sound directly related to engine or car speed? If so, can you tell which?

Is the loudness of the click related to throttle depression or engine speed? If so which?

Does it vary with engine temperature?

Does it vary with oil pressure?

Try dragging the brakes very lightly and see if that affects the clicking.

Try turning various accessories, especially the AC and blower, on and off to see if there's a change or cessation.

Does it go away, or change, if you declutch or coast?

You forgot to ask if it changes with the brand of gas he is using. If so were you using the same brand prior to this tank? (-:

Oops.

Actually my point goes further than that, do you notice a difference in how the C6 acts if you change major brands?

Dad, I haven't changed brands except a tank or two when travelling. I buy at a discount from a local supermarket, and they buy from BP (Amoco), which I consider a decent fuel. No differences that I noticed, but trips so far have been cruising the Interstate so driving differences would not be that noticeable.

I'm about to drive the thing KS -> FL -> SC -> FL -> KS, 4200 miles on lots of entertaining secondary roads, if it's of interest will keep track of gas brands, behaviors, and mileage for the group.

snip

Can't find it right now but there was a discussion about some of the major brands that were formulating a better gasoline than the others by GMs account. I read it just before my last trip south. Going down I bought any brand, coming back I bought the major brands that was talked about. Don't remember now which one they were though, I think Sunoco was one. Going down was 23 mpg and coming back was 32.8 and I'm sure some of that was driving style, very hot both ways. Big change for 4 tanks of gas and it could also be the 10,000 miles plus that was on it then. Although I seldom see a big mileage difference now as a new car is broken in.

Whatever, be safe out there,

Dad

Boy did I miss that, here's part of the information. Top Tier Detergent Gasoline is a new class of gasoline with enhanced detergency. It meets new, voluntary deposit control standards developed by BMW, General Motors, Honda and Toyota that exceed the detergent requirements imposed by the EPA.

Chevron in 29 states in the West, Southwest and South Conoco has over 4,000 stations located in 33 states. Phillips 66 has locations in 32 states.

76 has over 2,700 stations. QuikTrip in a few cities. Shell Shell Oil 7,000 gasoline stations in Western United States. Shell Oil 10,000 stations in the Eastern and Southern United States. Entec Stations in the greater Montgomery, Alabama area.

Mine showed a huge mileage difference as it was broken in - I agree, uncommon these days. Her initial cruise home from the dealer (180 interstate miles at 55-65 mph) gave 24 mpg and in her first week she delivered about 17-18 mpg commuting. By 6,000 miles she gave 21-22 commuting, 28+ at 75 mph, and 34-35 at 60. Biggest fuel usage change I ever saw a breakin bring about.

BTW the C6 was very slow to break in, she didn't really get settled in until about 6,500 miles.