Much better oil pressure after oil change.

[adriver]

MY owner's manual for (my 02 Silverado with a 4.8L/ LR4) tells me that the oil I should be using is 5W-30, and that 10w-30 is an acceptable backup. I notice a difference in the two. I notice a seat of the pants in difference in response (manual transmission, so yes I can notice it), and the 10W-30 maintains a more steady pressure, but its a little lower (around 60). The 5w-30 goes near 75 when cold, drops to about 50 at idle, and 65-70 when driving or getting on it. (I AM JUST GUESSING WHEN I SAY: ) to me, that seems like the 10w-30 is too thick, and only flowing as well as the pump is able to.

I'm not going to tell you which oil to use, but if I had to choose between going off of a random suggestion online that tells you to guess at it, or going off your owners manual..... Go read your manual..

 

[BG1988]

been using 5w30 mobil1 75PSI cold start

normals out to 55PSI idle..


you have been using 6qts correct?

 

[MrBiggs228]

Had this same issue but with a low mileage 04. End up being the motor was so neglected that oil and sludge were caked up

End up putting a rebuilt motor in

 

[OneofFew]

been using 5w30 mobil1 75PSI cold start

normals out to 55PSI idle..


you have been using 6qts correct?

Of course.

 

[OneofFew]

As to possibly using a higher viscosity oil- OEMs like recommending the thinner oil to get the fuel economy at the cost of longevity. In this case with lifter tick already evident at startup and the known lifter issues on the 5.3s , It may not be a good idea to go to a higher viscosity.

To all- I appreciate the great comments and suggestions

 

[SnowDrifter]

As to possibly using a higher viscosity oil- OEMs like recommending the thinner oil to get the fuel economy at the cost of longevity. In this case with lifter tick already evident at startup and the known lifter issues on the 5.3s , It may not be a good idea to go to a higher viscosity.

To all- I appreciate the great comments and suggestions

That's a pretty generous claim that a recommendation of lighter oils causes reduced engine longevity. I trust you have data or some sort of study we can reference?

 

[swathdiver]

That's a pretty generous claim that a recommendation of lighter oils causes reduced engine longevity. I trust you have data or some sort of study we can reference?

It does reduce longevity especially when they are running higher temperatures too. Grumpy Bear over on the GM-Trucks forum has been studying and posting about this for years with the K2s. I'm sure Blackstone-Labs has plenty of data too.

 

[SnowDrifter]

It does reduce longevity especially when they are running higher temperatures too. Grumpy Bear over on the GM-Trucks forum has been studying and posting about this for years with the K2s. I'm sure Blackstone-Labs has plenty of data too.

Save me a search through the hivemind?

 

[swathdiver]

Save me a search through the hivemind?

Pour yourself a cup of coffee and get your reading glasses on:

https://www.gm-trucks.com/forums/topic/190975-grumpy-bears-2015-silverado-2wd/

 

[SnowDrifter]

I only lightly skimmed the thread

But to be entirely honest I'm rather dissatisfied at both his testing methodology and conclusions. Though, as a disclaimer, I couldn't view the images he posted as I opted not to register an account for this one task. If he's posted any UOAs I'd like to review them.

1. He seems to be trying quite hard to correlate oil temp with effectiveness. I would argue it's more of a result of flow rate within the system rather than internal friction. After all, when an engine is running, everything operates on a hydrodynamic film. The parts don't actually touch eachother. It's possible he's measuring pumping losses but without any data on wear rates, those datapoints are meaningless.

2. OP ran out of the gate with a thinner oil than what the manufacturer suggested. Seems to contradict earlier points in this thread (the ones I challenged)

3. His comment/concern about oil frothing at the end of the thread is, I think, presumptuous. Again, too much time staring at numbers and trying to make conclusions rather than taking some measurements and observing results. Can't say oil is frothing based on a 3psi pressure delta. Would need a sight glass. Could potentially measure it, at least while flowing, with some sort of light diffusion test.

4. Oil film strength as a product as viscosity I think really undersells an interplay of multiple variables. We're not dealing with a static situation here. It's actively pumped and the oil film being replenished. Take it to the extreme of too thick and you won't have the flow rate to appropriately replenish the cushion of oil by the time the crank swings back around. you could also run into cavitation issues which would eat a bearing very quickly.

5. To be clear, my comment is on street vehicles. If you're racing, you should really know better than to run blind period. Everything will be determined per application. So don't go pulling up racing articles about oil viscosities showing wear rates. Those vehicles typically run a higher oil temp than you'd see during street use (duh) and actively need a thicker oil to compensate for temperature thinning. With that said, I maintain my point that MFRs aren't speccing thinner oil and seeing reduced engine life. I've yet to see any substantiating evidence that doing so reduces engine life. They're not going out and designing an engine then tossing whatever grade of oil in there is the thinnest they can get their hands on. Bearing tolerances, flow rate, bearing size (and by some extension bearing pressure/area) are all part of the design. If you do some poking on BITOG, a couple members have found benefit in running thinner oils in their engines, though once again, this is per application and the results determined through testing - it won't be indicative of every vehicle. Xw20 has been around now for over a decade. And while I hate to introduce personal experience as without documentation, it's more anecdotal than anything, I've seen dozens upon dozens of vehicles come in with 300k+ miles - taxi fleet stuff - that have been running the manufacturer recommended since day 1. Even had a couple 400k tahoes/yukons still ticking away on 5w30 - though one had some good rod knock. Always came in dipstick dry and overdue though, so no conclusion can be made here if an Xw40 would have been beneficial from a wear perspective (oil burning/leaking and owner negligence not withstanding)



So I suppose the debate still stands. Need concrete evidence that manufacturers are recommending thinner oil, which then results in a lower engine life.

Sorry OP for the thread hijack. If anyone's interested in continuing to discuss this, shoot me a note or we can make a new thread and continue jabbering there. I like our tech chats

 

[Larryjb]

It does reduce longevity especially when they are running higher temperatures too. Grumpy Bear over on the GM-Trucks forum has been studying and posting about this for years with the K2s. I'm sure Blackstone-Labs has plenty of data too.

Already there is an error here. My 2002 Tahoe runs at about 95C (200F), which is pretty much the same that my 92 Grand Marquis ran at. This was the same temperature that my 81 Lemans ran at. The water jackets surrounding the cylinders cannot be that much different from the block. The only variable I can see affecting the oil is that the oil may absorb more block heat than in the past, but I can't see that being an issue.

What I see as being a bigger issue is the design of the engine with tighter clearances. I found this article, which I would believe over a pseudo experiment "published" on a forum: https://www.lsxmag.com/tech-stories...rication-should-you-run-higher-viscosity-oil/

It is stated that a thicker oil will cause more wear than the lighter oil, because 70% of engine wear occurs on cold startup. You want the oil flowing to critical parts as fast as you can get it there.

 

[swathdiver]

It is stated that a thicker oil will cause more wear than the lighter oil, because 70% of engine wear occurs on cold startup. You want the oil flowing to critical parts as fast as you can get it there.

This is true. What's not mentioned is the thicker oils higher resistance to shear. A lower viscosity oil has less resistance to shear at higher temperatures then higher viscosity oils. If you can lower the temperatures, then you can reap the benefits of running the lighter weight oil. The engineers keep the temperatures up for emissions compliance, not performance or longevity.

PS> Just read the article and it is helpful but fails to mention temperature as the cause for shear falling off due to high rpms and horsepower. Heat makes horsepower, rpms generate friction and therefore heat.

 

[OneofFew]

IM kinda old school and live in the south. I just don't think 5w30 is the right choice for me in a climate that sees 100 degree heat and even in the deepest winter does not see temps below the teens. In the summer I run 10w30 in gas engines. All of my vehicles without cats run 15w40 HD diesel oil in summer. In over 2m miles run, I have never blown an engine.

I do still think that CAFE standards have influenced manufacturer's recommendations in viscosity and running a lower viscosity oil can effect longevity. Do I have proof? no. Is it possible that advances in oil technology warrants a change in viscosity recommendations? Yes.

 

[Rocket Man]

IM kinda old school and live in the south. I just don't think 5w30 is the right choice for me in a climate that sees 100 degree heat and even in the deepest winter does not see temps below the teens. In the summer I run 10w30 in gas engines. All of my vehicles without cats run 15w40 HD diesel oil in summer. In over 2m miles run, I have never blown an engine.

I do still think that CAFE standards have influenced manufacturer's recommendations in viscosity and running a lower viscosity oil can effect longevity. Do I have proof? no. Is it possible that advances in oil technology warrants a change in viscosity recommendations? Yes.

Does your engine run hotter in that environment than the rest of us? Or does the thermostat and cooling system maintain it, because in that case the outside temp doesn’t matter, correct? Or am I missing something?

 

[Larryjb]

I remember reading somewhere that the lifters are designed with smaller oil ports than previous engines, and this is part of the reason a lower viscosity oil is required. I do notice that my engine ticking on a cold start settles down quicker with 5W30 than 10W30.

 

[brasil]

in the late 90th i owned a 300SL Mercedes. With a six cylinder engine. The engine made a lot of noise ( lifters ) at start up in the morning. I asked a Mercedes engineer here in the town where I live- if he could give me a good advise. He gave me a very good one. He told me to switch from 10-40 over to. 0W 40. ...yes 0 w 40 ! followed his advise. Noise from the went away..after the first start up and the oil pressure even with hot oil....was still good.

The secret is the "0 "..this oil is very thin when cold...so the lifters are filled faster as with a 5 W or 10 w oil. While hot the 40 is the same as the 10w40 or 5w40...

Greetings Juergen

 

[iamdub]

Does your engine run hotter in that environment than the rest of us? Or does the thermostat and cooling system maintain it, because in that case the outside temp doesn’t matter, correct? Or am I missing something?

Of course. Our 100-degree heat is different than your 100-degree heat.

It's not the heat, it's the stupidity.

 

[BG1988]

That's a pretty generous claim that a recommendation of lighter oils causes reduced engine longevity. I trust you have data or some sort of study we can reference?

The correct answer is, when covered by a film of liquid sufficient to reduce the coefficient of static friction between the engine block and the piston/lifters etc... to essentially zero, but not so deep as to introduce a new source of friction.

 

[OneofFew]

Does your engine run hotter in that environment than the rest of us? Or does the thermostat and cooling system maintain it, because in that case the outside temp doesn’t matter, correct? Or am I missing something?

The reason colder climate oil recommendations are different is because of start up temperatures or do you disagree with that too?
Also, there is no means for regulating oil temperature on these. The colder the environment, the colder the engine oil.

 

[OneofFew]

Update: Oil analysis shows lead (15) from bearings and sodium(161) and potassium(47) from coolant. I have not been loosing any noticeable amount of coolant. I do have a lifter tap on cold start that gets louder when I raise the idle (at least I think it's a lifter tap) and get a 'low oil pressure' light when stopping to back into my driveway from the hill.
So my theory is that bottom end bearings are worn from coolant, lifters worn from age, etc, possibly an oil pickup tube O ring issue and an intake gasket leak resulting in cold engine stumble and a slight crack in the head or head gasket (not surprising given it's history of neglect)

Blackstone labs recommended increasing my oil change interval to 2k miles to reduce coolant accumulation.
I will try 10w30 dino oil and add some Lucas oil. If the bottom end is the issue, this should quiet that, if the lifters are an issue, this will exasperate that. No good solutions IMO, I think the engine is about done.