15-40 Oil?

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Originally Posted By: Honda2003
Is it ok to run 15-40 oil in my 2001 GMC.

It's OK to run 15W-40 in any engine but I recommend 0W-40 (preferred for gas engines) or 5W-40 (preferred for diesel engines) if you can afford it.
 
Well the antifreeze was the water pump. I got the pump changed and the thermostat with all new antifreeze. Both have never been changed since truck was new. Just waiting for my OCI to try something different.
 
Just added another 1/4 quart. That makes 1 full quart used so far on this OCI. I now have 1,244 miles on this OIC. So it used 3/4 quart first 600 miles and only 1/4 quart next 600 miles. Makes no since to me. Fixing to start putting a lot more miles on it. Cant wait till next OCI to try something different. Leaning on Delvac 1300 15-40. Just a update for anyone following.
 
Originally Posted By: Honda2003
Cant wait till next OCI to try something different.


tumblr_m0q1bwqvIs1rqnbfjo1_250.gif


Here's a thought...

Why not actually fix the problem? Oil consumption on these engines are well understood, and easy to address.

Running a 15w-40 (be is suggested by a mechanic, or someone on here) is merely covering up the underlying issue(s).
 
Since you have some miles to go before your next OCI, try adding a bottle of 'Restore' to the oil.

Silver can, comes in 4, 6, and 8-cylinder sizes. Helps consumption on older engines by 'filling in' cylinder scratches.

I've read of it working really well for some engines.
 
Originally Posted By: mazdamonky
You could also give a try to a 10w40 HMO. But running some Rotella HDMO may help do some cleaning which for some people seems to reduce oil consumption.


I switched my jeep with 4.0 in line 6 from 5w30 to 5w40 rotella T6. I went from a quart and a half in 3k to about 3/4of a quart in 5k. I have run it about 5 or 6 years now.

I have a 09 silverado and it just started using a little oil but I think the active fuel management is at fault. It only has 29k on it!😠
 
I cleaned the engine with kreen. Changed the pcv and put in castrol magnatec 5-30. It did not change consumption however my startup knock pretty much completely went away and engine runs real smooth. After the castrol i switched to maxlife 10-40 and the knock is back and that didnt help on consumption either. So back to magnatec on next change.
 
I changed my oil today. I went back to the Castrol GTX Magnatec 5w-30. Man i tell you with this oil there is no engine knock. Also i noticed it says full synthetic on this jug. The last jug had synthetic blend. With the Max life 10-40 it knocked real bad.
 
Good work OP, you gave both 10W40 and 5W30 a try, and found the Magnatec 5W30 works best for you. I assume you used the same type of filter both times.

That Magnatec is good oil, I've enjoyed a bit of it myself. It's well respected around BITOG. I've also been reading here that it has recently become a full synthetic in the 5W30 grade. The argument goes that Dexos1-Generation2 requires a full synthetic oil.
 
Actually I was ran a Wix with the change of Magnatec 2 changes ago and no knock either. I ran a Wix with the Maxlife as well. With this new Magnatec I picked up a Supertech filter from Walmart. The filter looks good just like the Wix also. No knock either. With the Maxlife it seem to knock pretty bad on every startup and even a little rattle when idling. Man its smooth with the Magnatec. This is what I'm gonna run from now on.
 
Yes, my car was very smooth on Magnatec too, I ran the 10W30 semi-synthetic in Euro A3/B4 grade. Different Magnatec to your ILSAC/Dexos grade, but it's common to hear "Magnatec" and "Smooth" in the same sentence. My car was so smooth and quiet, a few times when I was stopped at a red light, I had to look down at my instruments to make sure the car was still going (it was).

Magnatec is also producing excellent used oil analysis (UOA) with low wear numbers and good viscosity retention.

https://bobistheoilguy.com/forums/ubbthreads.php/topics/3849599/1
https://www.bobistheoilguy.com/forums/ubbthreads.php/topics/3940338/
https://www.bobistheoilguy.com/forums/ubbthreads.php/topics/4118200/

These are all with the Magnatec 5W30 syn-blend that you first used (SN, GF-5, Dexos1)
 
Well it is around 2qts in 3000 miles with the Magnatec 5-30. I tried the Maxlife 10-40 to try reduce consumption and not much difference if any. I changed it early to get rid of the knock. I've ran Valvoline conventional up until 75,000 miles. Then I switch to Maxlife. I ran it up until 3 oil changes ago. I tried Mobil 1 extended life 5-30 because someone told me it helped their Tahoe same year as my truck on oil consumption. Then I used Kreen to clean the engine. I ran it the last 1000 miles on the Mobil 1 then drained and filled with the Magnatec. Thats when I discovered the knock was gone. Then last oil change I use the Maxlife 10-40 to try reduce consumption again. Bad knock with it on start up. So I changed back to Magnatec today. No knock when I started it up. Very smooth running. Truck now has 223,000 miles on it. I bought it new and changed oil every 3000 miles.
 
My engine knock is back severely in this cold weather. Its time for a oil change now. Trying to decide on what oil to put in this time. Maybe its time for some kreen again to clean the carbon out.
 
Only way to know is try, living in Arkansas I don't see 15W-40 being a problem in winter since it doesn't get awful cold there.
 
Originally Posted By: Honda2003
My engine knock is back severely in this cold weather. Its time for a oil change now. Trying to decide on what oil to put in this time. Maybe its time for some kreen again to clean the carbon out.


What is cold weather right now in AR? Lows in the 30s and highs in the 50s? I'd just leave whatever you have in there.
 
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