What Oil Should I Use for GMC Yukon 2019 in a VERY HOT Summer

LDM

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Nov 8, 2018
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Illinois
Thank you all for your helpful comments. So I see that most replies see no issue in running 0w40 weight as I am doing right now. As it is time to change my oil now (6k miles) I went to my dealership and they warned me that using ANYTHING other than the 0w20 written in the cap would cause harm to the engine. They were shocked that I was using a 40 grade oil. No matter what temperatures they claim it doesn’t matter as “modern cars now use aluminum parts” which cannot tolerate heavy oil. It’s for Porche, BMW and high performance cars, not mine. Is this true? I’ve asked a few more people who agree with the dealer. I am CONFUSED now.

So far after switching to 0w40 I noticed my car performance better (a bit louder maybe when speeding) but overall I feel it’s fine. I was even considering running a 5w40 grade since it’s MUCH cheaper but now i am not sure.
Find a better dealership with more intelligent mechanics. 0W40 is exactly what is recommended for the LT1/4/5 engines, which are the same family of engines that the L83/4/6/7 are from.
 
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Thank you all for your helpful comments. So I see that most replies see no issue in running 0w40 weight as I am doing right now. As it is time to change my oil now (6k miles) I went to my dealership and they warned me that using ANYTHING other than the 0w20 written in the cap would cause harm to the engine. They were shocked that I was using a 40 grade oil. No matter what temperatures they claim it doesn’t matter as “modern cars now use aluminum parts” which cannot tolerate heavy oil. It’s for Porche, BMW and high performance cars, not mine. Is this true? I’ve asked a few more people who agree with the dealer. I am CONFUSED now.

So far after switching to 0w40 I noticed my car performance better (a bit louder maybe when speeding) but overall I feel it’s fine. I was even considering running a 5w40 grade since it’s MUCH cheaper but now i am not sure.
Definitely confusing on a lot of levels.
 
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My 6.2 l92 in a 2008 Yukon denali pulling a 8000 lb boat trailer combo has made it to 158k miles on 5w30 synthetic oils. If I were in op's climate I'd use 0w-40 mobil 1 like I use in my turbo cars.
 
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modern cars now use aluminum parts” which cannot tolerate heavy oil. It’s for Porche, BMW and high performance cars, not mine. Is this true?

Aluminium has been used for some time now. Rods, crankshafts and camshafts as well as a few other parts are still iron for the most part.
 
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Dec 27, 2019
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Nevada
Thank you all for your helpful comments. So I see that most replies see no issue in running 0w40 weight as I am doing right now. As it is time to change my oil now (6k miles) I went to my dealership and they warned me that using ANYTHING other than the 0w20 written in the cap would cause harm to the engine. They were shocked that I was using a 40 grade oil. No matter what temperatures they claim it doesn’t matter as “modern cars now use aluminum parts” which cannot tolerate heavy oil. It’s for Porche, BMW and high performance cars, not mine. Is this true? I’ve asked a few more people who agree with the dealer. I am CONFUSED now.
Ask them to explain in detail how using a 0w-40 will cause harm to the engine and they will reply with some watered down BS. Do the same when asking about how it is aluminum does not tolerate heavy oil. I can't even type this reply without laughing.
 

Jackson_Slugger

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Of course the manual suggests 0W-20 and I’ve followed that (ac delco 0w20) for the last 3 years since it’s new. Last time a mechanic told me I should never use the thin 0w20 since where I live there is no winter and it’s only for US. Our summer is very hot and I mean it reach 50 C (120 F) degrees in July and August. In winter temperature never goes below 3 C or 40 F and that’s even rare. Last time I used the Mobil 1 0W40 Euro but it’s too expensive ($14 Quart) and didn’t notice a difference. Should I try SHELL Helix Fully Synthetic? Or maybe 5W40 or Castro’s Edge 10W-60?

You also have an 8-quart sump or more, an oil cooler, and lots of these trucks running around just fine after well over 100K on 0W-20. If anything I'd buy up Mobil 1 0W-20 EP during rebate season if it's available "here"...

 
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I don't really care where you live, @GreySky - my guess would be you live either Down South where it is hot and humid, or maybe in a desert, which is hot and they SAY not humid though I wonder. Some people seem to really want to know.

If it were me, I'd run the thickest 20 I could find and call it a day. Or @High Performance Lubricants passenger car motor oil, probably a 5W-20 MAYBE a 5W-30, although there doesnt much seem to be a point, unless you truly believe that most oils today are sub-optimal and only for fuel efficiency. There is a case made here every 2 days about this, though I have become one to go with a manufacturer recommendation, a la oil cap. Plenty cars had 5W-30 oil cap specified back in the day, now those cars use 20 or 30 so....
 
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Doesn't it seem like a lot of mechanics in general give bad engine oil advice?
I stopped talking to one after he got all indignant on me after I told him "oil does not start out as a 5 and then go to a 30." That ticked me off.
 
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I would run the recommended oil untill the driv terrain warrenty is up. Then I would switch to a 5w 30 (full syn of course)
 
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Could be a basement in Delaware ?
download (2).jpeg
 
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