Another UOA = Used Oil Analysis, 07 Yukon Denali 6.2L w183k miles, Amsoil 0w-20 w/8.5k miles

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donjetman

donjetman

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I don't know enough about an OCA to determine what is good or bad, but I'm curious why you chose a 20wt oil for a 180K motor over the OE spec 30 wt?

Does the manual say a 20wt is ok for that year engine?

I know Amsoil is good stuff, I'm just thinking on the shear over time by beginning with a 20wt oil over a 30wt.
The report in post#1 shows that the oil didn't shear.
Is your Yukon AWD or RWD? Tires properly inflated?
AWD and always properly inflated which helps me achieve the great reliability and gas mileage.
New upstream O2 sensors over worn sensors can play a part with fuel economy.
as I stated in post#1 I changed all 4 recently
Another thought, if you compare highway MPG in the dead of winter as opposed to spring/summer, I agree, wind plays a big part. Cold, dense air is harder to push through, if you have flown light planes you know what I mean.
I'm a light aircraft owner (25+ yrs) and a retired pro pilot.
Overall it looks good, but if the iron is up over your other oil changes, what comes to mind is also the crankshaft journal, along with the before mentioned cylinder sleeve.

Again, above my pay grade, by personal thought is to stay with a 30wt...but that's just me.
Iron was much higher in reports 3, 4, & 5 when I was running 5w-30, but as I stated in post#1, there was an overheat event due to a broken heater hose T fitting shortly before sample#5 was submitted for analysis.

I learned on BITOG forum how thinner viscosity oil can flow a higher volume thus doing an arguably better job of carrying heat away and lubricating.

Like I said in post#1 = I drive conservately, I don't tow or hotrod.

I'm not certain what my next oil change will be with.
 

dkad260

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as I stated in post#1 I changed all 4 recently
Yes, I was just reiterating that point.
Iron was much higher in reports 3, 4, & 5 when I was running 5w-30
I was basing my iron statement of the Blackstone comment of your 0W-20 OCA, about the increase of iron. They basically said don't be too concerned and I trust that, again, over my pay grade.

Again, I think the OCA looks ok, I was just giving my $.02 on using a 20wt oil in a 180K mile LS engine, might be perfectly fine, only a different viewpoint.
 
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donjetman

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I don't know enough about an OCA to determine what is good or bad, but I'm curious why you chose a 20wt oil for a 180K motor over the OE spec 30 wt?

Does the manual say a 20wt is ok for that year engine?
no. My owners manual was written in 2007. A lot has changed since then, oils too.
what comes to mind is also the crankshaft journal, along with the before mentioned cylinder sleeve.
If crankshaft was shedding iron lead and copper from the bearing(s) would be thru the roof long before the iron from the crank shows up.
 

dkad260

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If crankshaft was shedding iron lead and copper from the bearing(s) would be thru the roof long before the iron from the crank shows up.

I would agree.


I was more or less adding to Dustin's inquiry on where iron would be found in an aluminum engine.
 
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donjetman

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I bought a stock 02 C5 coupe, only 60k miles. Rides smooth and gets great gas mileage.

Believe it or not? the C5 is gonna replace most of our Yukons trips of going back and fouth,1000 miles ea way, several times a yr between our 2 homes (TX & CO mtns). We no longer have large dog(s).

We'll still need the Yukons awd capability in the winter on the CO end.
 
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Geotrash

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I bought a stock 02 C5 coupe, only 60k miles. Rides smooth and gets great gas mileage.

Believe it or not? the C5 is gonna replace most of our Yukons trips of going back and fouth,1000 miles ea way, several time a yr between our 2 homes (TX & CO mtns). We no longer have large dog(s).

We'll still need the Yukons awd capability in the winter on the CO end.
Sorry to hear about the dogs, Don. :-(
 

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