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Old 10-21-2019, 01:50 PM   #1
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sagacious is on a distinguished road
Join Date: Nov 2010
Posts: 18
Default 2004 3.5L using oil, do I have low compression??


I have a 2004 Vue with the 3.5L V6 @ 178,000 miles and I've noticed that it's consuming oil in between oil changes. I have no idea how long it's been doing it since my wife used to drive it all the time but I did make sure the oil was always changed every 3k miles since we bought it used at 72,000 miles.

Anyway, since I just noticed this I don't know how quickly it's using oil yet but I'll start tracking it. So, my question is pretty generic at this point. Is there any other possible cause for oil loss besides low compression? I've already replaced the PCV valve and I don't see any visible oil leaks. I also don't see any engine oil contamination in my coolant or transmission fluid.

So, I topped off the oil yesterday and went driving around to let it warm up and then I floored it while looking in my rear view mirror to check for any white/blue smoke. I didn't see anything visible until sometime after the VTEC has already kicked in, maybe around the 5,500-6,000rpm that point just before it shifted I saw a white puff that dissipated pretty quickly.

so, I am fairly concerned about worn piston rings at this point but I've been watching my short term and long term fuel trims and I should be able to tell from that, right? Because... if I had a low compression issue, there would be excess raw hydrocarbon in the exhaust system and the O2 sensor would read this as rich and the computer will lean out the mixture (causing negative fuel trim) to compensate. However, I don't have negative fuel trims. My Short term fuel trims stay positive in the 1-3% range and my Long term fuel trim stays in the positive from 0-1.6%. Any ideas what's going on??
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