Factory calls for 5w30 but.....

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286
Location
Bay City Michigan
My 2008 Silverado "Vortec Max" 6.0 calls for 5w30 year round. To sum things up quickly, I have installed an aftermarket computer tune, and an aftermarket exhaust system. I drive this truck HARD including heavy towing, and also some off road fun (sand-dunes) Do you oil guru's think I should still stick with the 5w30? I am running the highly popular Pennzoil platinum...and have not bothered with a UOA yet due to break-in. I now have just over 27,000 miles on her. I was thinking going to PP 10w30 in the summer due to the slightly better NOACK, and slightly better HTHS numbers. I know that these factory hand held tuners can create more stress on engines, and am looking for anyone in the same boat as me who has done UOA's on slightly modified engines to chime in.
 
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3,756
Location
CA
It makes sense to go with the 10w-30 since you're working the engine beyond the factory limits. More shear resistant and possibly better high temp protection. If it were mine I would take it a step further since you're going to be running higher oil temps, I would use a 40wt. It will likely be as thin as a 30wt under the heavy towing anyway.
 
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Patman

Staff member
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21,985
Location
Oakville, Ontario
My Corvette is slightly modified, with an aftermarket tune and a cold air intake (Vararam) and I'm getting good UOAs with PP 5w30, even when I drive it hard in the summer and even when I've made a few quarter mile runs (along with lots of full throttle blasts on the street) So I see no reason why you can't stick with PP 5w30 all year round. I honestly don't think there is any real tangible benefit to switching to PP 10w30. On paper it might look slightly better but the UOAs I'm getting show that PP 5w30 is already up to the task.
 
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47,534
Location
Duvall WA - Pacific NW USA
I really doubt it will make much difference in the grand scheme of things (5W-30 vs. 10W-30) unless you find an oil that is 10W-30/SAE 30 with no VII's. Jumping to a modern XW-40 may be a good move if you have high heat/high load situations where the engine may not get adequate cooling.
 
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1,093
Location
Kentucky
 Originally Posted By: Pablo
I really doubt it will make much difference in the grand scheme of things (5W-30 vs. 10W-30) unless you find an oil that is 10W-30/SAE 30 with no VII's. Jumping to a modern XW-40 may be a good move if you have high heat/high load situations where the engine may not get adequate cooling.
\:\! I put M1 15W-50 in my 2008 at the beginning. I changed at 500, 2000, and 5000. It now has 6400 on it. Runs great, gets averages better, much better, than EPA estimates. It does have a camper pack.
 
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136
Location
NC
Been running 5w30 for 161000 mile now on 6.0 engine. Have had it tuned for 61000 miles, aftermarket exhaust for all its life and bigger tires. Senn pleny of offroading, so the stress has not botherd it at all.
 
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682
Location
ontario canada
I like synthetic 10w30 because it has the same cold properties as a corresponding 5w30 conventional, much less volatility and more shear stable. In winter run the 5w30 synthetic, because it has AWESOME cold properties. It sounds like the truck is being used more in the summer, and the 10w30 will stay in grade better than the 5w. and so it will tolerate a longer OCI.
 
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207
Location
USA
I know a mechanic, friend of the family, who was trained and certified in a GM mechanic program. Excellent mechanic. He recommends 10w30 in all full size GM trucks year round instead of the 5w30 the manual recommends. Again, not an expert myself, I'm sure the big boys like the 3500's or bigger would be an exception to his rule.
 
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434
Location
MD
what does is matter if it's a 5w30 or 10w30? Once they are up to temp they are exactly the same. If you want a more shear stable oil than you need to look at a 40W.
 
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Messages
3,756
Location
CA
 Originally Posted By: Badlees
what does is matter if it's a 5w30 or 10w30? Once they are up to temp they are exactly the same. If you want a more shear stable oil than you need to look at a 40W.
Not exactly...
 
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1,283
Location
Canada City, Canada
 Originally Posted By: 360kid
I know a mechanic, friend of the family, who was trained and certified in a GM mechanic program. Excellent mechanic. He recommends 10w30 in all full size GM trucks year round instead of the 5w30 the manual recommends. Again, not an expert myself, I'm sure the big boys like the 3500's or bigger would be an exception to his rule.
Far too many people just assume that a mechanics word on motor oils is good. These guys aren't engineers, they don't lab test these oils, and their opinions are usually based off of myths and stereotypes. Most will tell you a 0w30 is to thin to protect a vehicle that calls for 5w30. If I want to know a good place to eat, I don't ask my dentist. (This was no way directed at your mechanic as he/she may or may not know what they are talking about.)
 
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1,093
Location
Kentucky
 Originally Posted By: Badlees
what does is matter if it's a 5w30 or 10w30? Once they are up to temp they are exactly the same. If you want a more shear stable oil than you need to look at a 40W.
Not exactly. Mobil 1, for example, makes a deal out of the fact than their 5W-30 is considerably thicker at temperature than their own or most anyone elses 10W-30. The reason given is that so many cars call for 5W-30 and they make a 5W-30 in the range of some older 10W-30's for extra protection. Other brands do this also but not at the same level of Mobil 1. While searching I ran across one 5W-30 that was almost a 40, 12.3 or something. I think there are also some raeally thick 0W-30's. A 0W/5W/10W-30 will all be 30 grade at temperature but one may be just barely above a 20 and another almost a 40.
 
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