15-40 Oil?

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Is it ok to run 15-40 oil in my 2001 GMC. It is z71 5.3 4x4 ex cab. I had a mechanic tell that I should run a thinker grade than I currently use. I use 5-30 now. Said he ran SuperTech 15-40 in everything he owns. I've thought about trying it because of my quart or more oil burning during 3000 mile oci. I've actually thought about switching to Delvac 15-40. I currently use Mobil Super 5-30 and used Maxlife 5-30 before that. Bought the truck new and it now has 213,000 miles it.
 
Keep using 5w-30. I think that's what GMC calls for.

If I were to run a thicker oil, I'd consider using a 5w or 0w-40 instead of 15w-40.
edit: Just noticed the oil burning, 10w30 could be a decent idea.
 
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The 5.3 is a full roller motor. It doesn't need thick. 15W40 will be fine, but I would stick with 5W30 myself.

If you are burning a quart per 3000 miles, switch to 10W30 maxlife, and maybe try their 10W40 if you really want to try a 40 weight.
 
A 15w-40 is certainly acceptable. But, unless the specified 5w-30 is giving you real, tangible concerns, why change? Is your oil pressure low? Is it leaking out and a thicker oil would leak more slowly? Is it consuming oil? Try something like 15w-40 if you wish to address such issues. If you don't have such concerns, you'll be fine with what you're already doing.
 
Nothing wrong with 15W-40, it's probably the most common oil weight in Australia. 15W-40 mineral and 10W-40 semi-synthetic. We run it in everything.

Nothing wrong with a good 5W-30, but if you want to try 15W-40 it's not going to hurt your truck. You could always try it for one oil change and see, if you don't like it go back to 5W-30.
 
No. Don't run 15w40. If your problem is oil burning, run M1 High Mileage 10w30 for at least a 6000 mile oil change interval.
 
You live in AR and are burning oil - you could move up a grade if you want, though staying with 5W30 won't hurt, either. I'm sure 15W40 wouldn't hurt anything, but I might be inclined to try a 10W30 or 10W40 HM oil.
 
Originally Posted By: Garak
A 15w-40 is certainly acceptable. But, unless the specified 5w-30 is giving you real, tangible concerns, why change? Is your oil pressure low? Is it leaking out and a thicker oil would leak more slowly? Is it consuming oil? Try something like 15w-40 if you wish to address such issues. If you don't have such concerns, you'll be fine with what you're already doing.


Yes, I think he said in the first post that the truck is consuming more than 1 quart in 3000miles.
 
My question is were you burning oil on Maxlife? you were using an HMO which is supposed to help with oil consumption but moved to Mobil super. Maybe try Mobil super High mileage? It can be had here in AR for $15.17 plus tax with a $7 mail in rebate at the time, so I see absolutely no harm in giving it a go. (if you have been using regular mobil super)
 
The answer to your question is yes it is ok. I have had two service trucks that were run exclusively on 15w40 before i bought them. One a 5.4 ford and the other a 5.7 chevrolet. If you switch i would run a short cycle of 2500 miles or so at first due to the high detergents of the 15w40, your dipstick will be black from the cleaning.
 
Oh, Also, to answer your question, being here in Arkansas, I would Imagine 15w40 wouldn't hurt at all. Especially during the summer.
 
Originally Posted By: zrxkawboy
You live in AR and are burning oil - you could move up a grade if you want, though staying with 5W30 won't hurt, either. I'm sure 15W40 wouldn't hurt anything, but I might be inclined to try a 10W30 or 10W40 HM oil.


+1 I worked for a landscape company when I was in college and he used 15w-40 shell in his entire fleet. Gas and diesel. We had an irrigation truck that had 300k on it and still purred like a kitten. Personally I don't see there being any issues but consider switching to a 10w-40 HM like Pennzoil.
 
Originally Posted By: Thebimmerfan
Yes, I think he said in the first post that the truck is consuming more than 1 quart in 3000miles.

Thanks, don't know how I missed that. It might be worth a try, but that consumption isn't that high. It's on the border of what I'd consider annoying.
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Yes I was burning oil on Max Life. Quart or more on OCI 3000 miles. I've been on Max Life since 75,000 miles and now have 213,000. I just switched to the Mobil Super High Mileage 2 changes ago. No different than the max life and both 5-30.
 
I had actually switch to the Mobile super high mileage because someone told me it stopped there oil usage in a 2001 Tahoe. I also wanted to see if it would help on that start up knock that I've had since 20,000 miles which is very annoying.
 
Originally Posted By: Garak
Originally Posted By: Thebimmerfan
Yes, I think he said in the first post that the truck is consuming more than 1 quart in 3000miles.

Thanks, don't know how I missed that. It might be worth a try, but that consumption isn't that high. It's on the border of what I'd consider annoying.
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Yeah, I think that consumption is still in the tolerable limits (the upper ones), but if with 15W-40 consumption can be reduced and/or eliminated it's a win. I'm sure this a little more viscous grade won't hurt anything - just the contrary.
 
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.
 
How about the new Maxlife Heavy Duty 15w40? I've been considering using it in a 02 Forester N/A that leaks like a seive. The owners manual says that 10w40 is acceptable though. Not sure what the thickest grade your manuals says.
 
I didnt know they had a new one. I'm not sure what I'm going to try yet. I got a oil change coming up in about 500 miles though. What bugs me is that I see lots of other trucks same motor same miles or more or little less with no oil usage. I have changed my oil religiously since I bought this truck new.
 
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