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Upon delivery I had some small xfer case drips, wiped those away, haven't returned. This is the second round for trans bell housing drips, both fresh oil, so I'm thinking there's a bit left over in the bellhousing....


I'm not terribly concerned but will keep an eye on it for sure. I drained a little over 9 quarts, added 10 for a full fill.
I don’t know if you do this, but if you drive the front on ramps/blocks where it’s higher than the rear, you’ll get a little more oil out when draining.
The pan design tells it all.
 

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Discussion Starter #42 (Edited)
I don’t know if you do this, but if you drive the front on ramps/blocks where it’s higher than the rear, you’ll get a little more oil out when draining.
The pan design tells it all.
Thanks DRC, I do use the ramps, lol, I couldn't fit under the truck otherwise! the motor was a little cooler than I usually like and I didn't let the oil dribble out as much this time due to high winds kicking up sprinkling the front drivers tire 'dunno; so i buttoned it up a little quicker than normal and then used liberal amounts of the Simple Green.
 

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Discussion Starter #43
I'm sitting at just over 6k on the odometer, today she gets another Mobil1 Oil Filter and Rotella T6, 5k intervals from here on out!

 

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the good old days, where the engines was built with sloppy clearances where you could even run a straight 50w oil in the winter months and still have lots of oil vapor blow-by and even more clatter...…….....Todays world tighter clearances, not much piston slop, lighter weight oil and very little blow-by...…….

I use AC/Delco actually they don't manufacture much of anything anymore all sub'd out.
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I hope you meant well - yes - that portion of your post dealing with modern manufacturing is correct - most of what we buy today for our vehicles is made by huge plants , often overseas, who package and decal the product to suit whatever "name brand" sub-contractor they are dealing with. I get a kick out of folks who think one "brand" of, for example, 15-40 oil makes their truck run better than some other brand. Be assured "litigation conscious" major sales entities are not interested in incurring expensive law-suits and bad public relations. If it is a name brand sold in a legit. facility it is going to meet SAE/ASTM standards, and thus be no different from any other.

As to your statement about machining standards - what purpose do you think you serve by posting such utter nonsense. True, motors last longer these days because of the superior oils developed during the 2nd World War, and the industry-wide adoption of full-flow oil filters ( plus better induction air filters) of the last forty or fifty years or so. And, of course, the industry-wide adoption of "modern" chrome piston rings (someone correct me if I am wrong, but I believe the Packard Twelve of 1937 started that trend).

As far as piston skirt, ring-land, rod and main bearing clearances - suggest you familiarize yourself with basic machining standards down thru the years before making such statements. Now - to be fair, what COULD have confused you is the difference in piston skirt clearances in air-cooled motors, such as we have in airplane motors. Given thermal/expansion issues yes those clearances would be greater than any "modern" (meaning "new limits" standards found in any Motor manual published since after the FIRST World War.
 

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I hope you meant well - yes - that portion of your post dealing with modern manufacturing is correct - most of what we buy today for our vehicles is made by huge plants , often overseas, who package and decal the product to suit whatever "name brand" sub-contractor they are dealing with. I get a kick out of folks who think one "brand" of, for example, 15-40 oil makes their truck run better than some other brand. Be assured "litigation conscious" major sales entities are not interested in incurring expensive law-suits and bad public relations. If it is a name brand sold in a legit. facility it is going to meet SAE/ASTM standards, and thus be no different from any other.

As to your statement about machining standards - what purpose do you think you serve by posting such utter nonsense. True, motors last longer these days because of the superior oils developed during the 2nd World War, and the industry-wide adoption of full-flow oil filters ( plus better induction air filters) of the last forty or fifty years or so. And, of course, the industry-wide adoption of "modern" chrome piston rings (someone correct me if I am wrong, but I believe the Packard Twelve of 1937 started that trend).

As far as piston skirt, ring-land, rod and main bearing clearances - suggest you familiarize yourself with basic machining standards down thru the years before making such statements. Now - to be fair, what COULD have confused you is the difference in piston skirt clearances in air-cooled motors, such as we have in airplane motors. Given thermal/expansion issues yes those clearances would be greater than any "modern" (meaning "new limits" standards found in any Motor manual published since after the FIRST World War.
My comment was based on excessive blow-by where we ran straight 40w standard and eventually straight 50w oil with diesels compared to todays machining standards, tighter clearances, where you can run 5w-40 or 15-40 even 0-40, which is still very thin compared to a straight 40w.
Apparently you don't have much back ground building motors in the 60's, 70's and 80's I do, and the oil blow-by they had with a open PCV puffing oil vapors down the highway with 40 and 50 weight oil.
Several of my trucks while idling and setting would leave its oil mark on the ground underneath, like a male dog would leave on a fire hydrant.

A few freak out about people doing PCV re-routes today, because they refer back to the old days with excessive blow-by coating the highway, that my friend was the utter nonsense subject I was talking about, comparing the good old days machining standards to todays machining standards.

I'm referring to Cummins, Cat and International, remember the Duramax was not even consumed yet.
Here's the recommended specs below for Duramax.
https://www.ppediesel.com/shop/pub/media/pdf/DuramaxForgedPistonAndRingInstallationGuide_v3.pdf

Back in the 60's, 70's & 80's the engines had no less than 3 times more clearances compared to todays standards
which = more oil blow-by, that's why we ran heaver weight oil.
The newer engines have very little if any blow-by with a re-route, with tighter engine clearances.
I did search for specs back in the 60's, 70's & 80's for you, but unfortunately the internet search doesn't go back that far.
If your still not happy with my explanation 'dunno; what to tell you, except by-by.
The only air cooled motor I've mess with is a lawn mower, generators, I don't think these count for being a expert on this subject, like you are.
But that wasn't back in the good old days either.

Even the gas engines back in the good old days had more clearance than the Duramax suggested clearances.
Running straight 30w then 40w up to 50w, straight 50w Pennzoil racing oil is what I ran in my race car 1970-1983.
 

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Discussion Starter #48 (Edited)
Next weekend I'll be right at 10,000 miles; bought 3 gallons of Rotella T6 15w-40 and a Mobil1 filter with a Feb 2019 date code. Was happy to see my local Walmart carried the new-ish Rotella T6 blend. Going with the thicker oil for the hot summer months we have in Vegas. I'll switch back to 5w-40 for the winter. So far so good, no issues to speak of. Also going to drain and fill transmission fluid/change trans filters soon along with replacing the fuel filter (bought a 36mm socket for the fuel filter housing) then do a chassis lube when I finally break out my grease gun from parts unknown! (nothing fancy just some NLGI 2 rated lithium chassis grease).
 

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T6 is a full synthetic 5/40 oil. Rotella T5 is a 15/40 synthetic blend - maybe that is what you are running? 15/40 is not a ‘thicker’ oil at higher temperature when compared to 5/40 they have the same viscosity at 100 degrees celsius. The benefit of 5/40 is that it is a full synthetic which should not break down as quickly as a semi or non synthetic oil and the 5/40 provides lubrication quicker on start up.

When I lubed my front end I found that the sockets were dry - all of them! I thought maybe they forgot to lube mine but I did read on here somewhere that GM sends them out without any grease - not sure why...
 

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Discussion Starter #52
thanks guys, I did in fact get Rotella T6 15w40, $22 bucks a gallon w/$7 mail in rebate per gallon from Rotella = sweet deal mang!
 

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I am obviously missing something here so I have to ask why would you want 15/40 instead of 5/40? Shell has the rebate on the 5/40 too.
 

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Discussion Starter #54 (Edited)
I am obviously missing something here so I have to ask why would you want 15/40 instead of 5/40? Shell has the rebate on the 5/40 too.
A few things went into selecting the T6 15w40 for the summer over the 5w40. As previously stated, the first would be the high average temperature in Las Vegas. Its not uncommon for it to never get below 80's in the summer with highs in the 105-115 range. I would say that's the main reason but also I felt comfortable running T6 5w40 in the winter because, believe it or not, we do get a freeze on a few nights and sometimes into the 20's. Also, 15w40 is the recommended oil weight with 5w40 as an alternate recommendation. I'm sure the 5w40 would be just fine, I just feel more confident running the 15w40 in the summer. I'm not sure how Rotella achieves the 15w40 rating but I'm speculating (guesstimating/hoping) it starts with slightly heavier base stock.
 

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40 is 40, as far as heat goes.

In Summer, it's not uncommon to still be in the 90s @ Midnight 'round here...100* before Noon. I run 5w-40 full syn year round.
 

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I would’t feel comfortable using 5-40 durning hot summers like we have, especially when towing.
Our temps are in the 115-120 durning the summer months.
I run 15-40 syn blend year round, when and if it gets around 25-35, that’s when you should let’er warm up a little before you start driving.
Moregrip :thumb
Do what makes you feel comfortable, it’s your truck.
 

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Discussion Starter #57 (Edited)
Here's a good representation for my decision (among other research):

https://www.machinerylubrication.com/Read/30197/choose-engine-oil

Overall Rotella T6 seems like a pretty decent oil in what is most likely a Group III base stock.

Although I haven't read anywhere that the T6 15w40 uses a heavier base stock it makes fairly good sense that it "most likely" does.

https://rotella.shell.com/en_us/products/full-synthetic-and-blend-oil/shell-rotella-t6-15w-40-full-synthetic-motor-oil/_jcr_content/par/productDetails.stream/1554344185567/6aaeba0ca380ce31c1a45ba16a94dded7f4aea73/shell-rotella-15w-40.pdf

Lastly, I don't believe we are really talking about all that much of a differnce and both would work well year round, but for me and the way I think, it made enough sense to make the small change for the summer season.
 
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