Zigglefuss
New Member
- Joined
- Sep 25, 2008
- Messages
- 4
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9/17 Bought new 5.3L Z71 2WD Tahoe with 95 miles on it
9/29 Drove with family 2 hours on highway with cruise at 70mph w/ AC on and tire pressure in the 37/38 psi range when tires warmed up (tire PSI is 33/34 cold) = AVG 19mpg
10/18 Changed oil and filter at 1000 miles (one of those people who just feels better about doing this with any new car). Put in 6 quarts of 5w-30 synthetic, did not check dipstick-just followed amount indicated in owners manual). I noted a little less than 5 quarts drained out.
10/19 Drove with family an hour on same highway as 9/29 with cruise at 70mph w/ AC on and tires still in the 37/38 range = AVG 16.5mpg
10/20 Guessing I overfilled the oil, I drained 1 quart out from the oil pan.
10/21 Drove with family an hour on same highway as before with cruise at 70, AC on, 37/38 psi = AVG 19.4mpg. Checked oil level after dinner before turning around and it was fine...just above the second hole from the bottom and within the hashed area. MPG was 19/20 mpg on the way home, but speed was variable (a bit slower) and without using cruise as much.
Gas used on all trips was from either Sam's or BJ's and both can contain up to 10% ethanol. Outside air temp was very similar.
Can't really bring myself to believe 1 quart of extra oil could have that level of impact, but I can't think of any other variables to explain it.
Can anyone think of another explanation or something I'm missing?
9/29 Drove with family 2 hours on highway with cruise at 70mph w/ AC on and tire pressure in the 37/38 psi range when tires warmed up (tire PSI is 33/34 cold) = AVG 19mpg
10/18 Changed oil and filter at 1000 miles (one of those people who just feels better about doing this with any new car). Put in 6 quarts of 5w-30 synthetic, did not check dipstick-just followed amount indicated in owners manual). I noted a little less than 5 quarts drained out.
10/19 Drove with family an hour on same highway as 9/29 with cruise at 70mph w/ AC on and tires still in the 37/38 range = AVG 16.5mpg
10/20 Guessing I overfilled the oil, I drained 1 quart out from the oil pan.
10/21 Drove with family an hour on same highway as before with cruise at 70, AC on, 37/38 psi = AVG 19.4mpg. Checked oil level after dinner before turning around and it was fine...just above the second hole from the bottom and within the hashed area. MPG was 19/20 mpg on the way home, but speed was variable (a bit slower) and without using cruise as much.
Gas used on all trips was from either Sam's or BJ's and both can contain up to 10% ethanol. Outside air temp was very similar.
Can't really bring myself to believe 1 quart of extra oil could have that level of impact, but I can't think of any other variables to explain it.
Can anyone think of another explanation or something I'm missing?
