10W40 HM oil in a Chevrolet 4.2L inline 6?

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Guys,

I picked up a bunch of 10W40 HM full synthetic oil (both M1 and Castrol) at the AZ clearance a few months ago. My plan was to use it on my son's 2003 Hyundai Santa Fe which specs all KINDS of weights in the owner's manual. I still plan to do that, but I got so much I was thinking about using it on my daughter's 2002 Chevrolet Trailblazer with the 4.2L too (even though it specs 5W30). Thoughts? Has anyone had issues running a 40 weight in this engine? Should I be OK? I live in Texas so it never gets too cold.

Thanks in advance...
 
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It should be fine
smile.gif
 
Originally Posted By: slacktide_bitog
It should be fine
smile.gif

+1

I’m running that clearance oil in my Jeep now.
 
Run it, I ran 0w-20 in that motor for 10k miles. It doesn’t care.

Plus, the FE is so bad in a Trailblazer that you can’t see the difference.
 
I put 10w30 in any Atlas engines that come through my shop with any mentionable mileage, anyway. Shouldn't hurt a thing, especially being synthetic.
 
Cool--thanks, guys. Yeah, I'd never even seen 10W40 in a full synthetic but it was such a good price I had to pick it up. I got 10 quarts of the M1 and 14 quarts of the Castrol back in December/January. :)
 
Originally Posted By: mrdctaylor
I was thinking about using it on my daughter's 2002 Chevrolet Trailblazer with the 4.2L too (even though it specs 5W30). Thoughts?


Run up to Atwood's in Lacy Lakeview
and get 5qts of full synthetic Harvest King 0W-20 for $11....

then mix it 50/50
(that's my plan)
 
Originally Posted By: Linctex
Originally Posted By: mrdctaylor
I was thinking about using it on my daughter's 2002 Chevrolet Trailblazer with the 4.2L too (even though it specs 5W30). Thoughts?


Run up to Atwood's in Lacy Lakeview
and get 5qts of full synthetic Harvest King 0W-20 for $11....

then mix it 50/50
(that's my plan)


Wow! $11? I've actually never been to Atwoods. I work at Baylor so I'm not that far from that area during the week. Any idea who makes that oil?

Also, for anyone who cares here is the oil I'm talking about...
 
Did a little searching and I guess RK oil is either made by Citgo or Warren, right? Regardless, that is a heckuva price. Of course, I have almost 100 quarts of oil at the house now, so I won't be buying any for a while...or at least until the next Auto Zone clearance. :)
 
Originally Posted By: Linctex
get 5qts of full synthetic Harvest King 0W-20 for $11....

then mix it 50/50
(that's my plan)


Back to this...so if you mix it 50/50 would it actually be a (roughly) 5w30? Or does it not work like that?
 
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I don't know why 10W40 went almost extinct anyway. It seems like the perfect weight in temperate climates for an engine with any amount of miles on it.

Sheer stability HAS to be better now than it was when this was almost the default oil weight in the 1970s and 1980s. None of my engines would even blink at running 10W40 unless it was below zero. Engines died early deaths decades ago not from 10W40, but from automatic chokes on carburetors giving a free "gasoline wash-down" to the cylinder bores on every cold start.
 
Originally Posted By: Scdevon
I don't know why 10W40 went almost extinct anyway. It seems like the perfect weight in temperate climates for an engine with any amount of miles on it.

Sheer stability HAS to be better now than it was when this was almost the default oil weight in the 1970s and 1980s. None of my engines would even blink at running 10W40 unless it was below zero. Engines died early deaths decades ago not from 10W40, but from automatic chokes on carburetors giving a free "gasoline wash-down" to the cylinder bores on every cold start.

In Europe until the 80s almost all cars spec'd 20W-50, and until about 15 years ago stil a lot spec'd 10W-40 Syn-blends for most climates.
 
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