Just looked up my records. I've never gone over 5000 miles between oil changes. At 46K miles, I have 10 oil changes. I hope that will help. I also installed the disabler last year. I've still had a few times when it didn't seem to engage (which I can tell because the start stop feature kicks in), but for the most part, I think it's working. For some reason, GM did not include the number of cylinders running in the information screen like I had on other models. In my Cadillac, it shows me when it's running on 4 cylinders on the fuel milage screen. I can't find that on my '21 Denali.
Melling I believe is/was the OEM on the lifters who explored this problem some years ago. The white paper they generated on the topic indicated two items of note when I read it. 1.) They only fail on the switch. Prevent the switch, prevent the failure. 2.) The majority fail due to deposits messing up the timing of that switch. Anyway that's what I got from it.
Mine have always been active, 195K+ now, and my oil maintenance is surgically clean.
Of course this assumes good parts. That is no heat treat issue or machining flaws. I get comfortable that these issues are in the rearview mirror by about 30K. IMHO naturally.
Yes, the key seems to be with the half tons that if it has the Z71, then it definitely has the two speed. What got me was that the two speed AND the lower geared towing package option could not be chosen together the last few years unless it was mated up to the 6.2. Want the 3.0 duramax and 3.73 tow gears ... nope, can't get the two speed transfer case ( neighbor son realized that after he had bought his used 3.0 half ton .. where the frick is the low range ? ! ).
I am still unsure which truck series, the half ton or the HD truck that the original poster is referring to for sure other than yes his question is in the HD section of this forum but that doesn't guarantee the question got asked in the right section.
read your owners manual. there's only a few specific modes where recirculation can be turned on, and it automatically switches to fresh air if you change to the hvac to a mode that doesn't support it.
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