OLM was tripped on the GM so I changed the oil....

Status
Not open for further replies.
Originally Posted By: Warstud
A thick 5w20 can = a thin 5w30


Really, so a "thick" 5w-20 with an HTHS of 2.7cP is the same as a "thin" 5w30 with an HTHS of 3.0cP?

If an oil is a 5w-20, it is labelled as 5w-20. If it is a 5w30, it is labelled as a 5w30. They are not "equal". While fuel dilution and/or shear on a 5w30 that starts on the lower end of the 5w30 range may drop it into 20-weight territory, that is NOT the same as a 5w-20 that starts out at that viscosity.
 
The wrong viscosity oil is the least of this poor truck's problems. It has no idea what its in for.
 
Originally Posted By: 901Memphis
That GM engine needs a 30 grade to maintain proper hot oil pressure, it looks like the dash has an oil pressure gauge did you notice a big drop?


Dude you are way behind here. He said the gauge stayed the same, Lucas or no Lucas, 20 or 30.
 
I say let him run what he wants. He will anyway. If the engine destroys itself on the 5W-20, then everyone can tell him "I told you so" and he will have learned a valuable lesson.

Wayne
 
While I don't think using a 20 grade is a huge deal if the vehicle isn't going to be run hard I thing Chevy knows their stuff when it comes to their engines.
I used a 5w-20 in a 5.0 fox for a while. Engine had more pep off idle. It's a 5 speed.
Chevy v8 engines are known for their reliability and longevity and I feel it has to do with the design and the oil spec. Not to mention various oil coolers built in to the rad etc.
With this high mileage engine going thinner may not be prudent. The 5w-20 will burn off fairly quick so I'd buy a couple quarts of 20w-50 to use as top up then stick with the 30 grade spec from here on out.
Will going thinner cause harm? Quite possibly. Drive it easy.
 
Originally Posted By: kschachn
Originally Posted By: 901Memphis
That GM engine needs a 30 grade to maintain proper hot oil pressure, it looks like the dash has an oil pressure gauge did you notice a big drop?


Dude you are way behind here. He said the gauge stayed the same, Lucas or no Lucas, 20 or 30.


Exactly, plus I can tell you from experience that the oil pressure gauges for these vehicles are nothing more than a glorified idiot light at best.

When I had my 2005 Trailblazer (same 4.2 engine) I had some left over 20W-50 oil in the garage. We were having this discussion on one of the forums for this vehicle, so I decided to try it. After 1,000 miles, it was clear - the "gauge" had the exact same readings as when I used 5w30. For example - same 40 "psi" at idle regardless of whether the engine was hot or cold.
 
Originally Posted By: wtd
I say let him run what he wants. He will anyway. If the engine destroys itself on the 5W-20, then everyone can tell him "I told you so" and he will have learned a valuable lesson.

Wayne


He won't learn a bloody thing. His track record is proof of that.
 
Originally Posted By: Clevy
While I don't think using a 20 grade is a huge deal if the vehicle isn't going to be run hard I thing Chevy knows their stuff when it comes to their engines.
I used a 5w-20 in a 5.0 fox for a while. Engine had more pep off idle. It's a 5 speed.
Chevy v8 engines are known for their reliability and longevity and I feel it has to do with the design and the oil spec. Not to mention various oil coolers built in to the rad etc.
With this high mileage engine going thinner may not be prudent. The 5w-20 will burn off fairly quick so I'd buy a couple quarts of 20w-50 to use as top up then stick with the 30 grade spec from here on out.
Will going thinner cause harm? Quite possibly. Drive it easy.


For right right now, I thickened it out by adding a quart of the 20W-50. It is due for an actual OCI in 1500 miles.

Originally Posted By: OVERKILL
Originally Posted By: wtd
I say let him run what he wants. He will anyway. If the engine destroys itself on the 5W-20, then everyone can tell him "I told you so" and he will have learned a valuable lesson.

Wayne


He won't learn a bloody thing. His track record is proof of that.


I have a response to this. Hear me out..

Ever think that I got sick of making engines rod knock with MMO hijijx and shenanigans? This vehicle has been maintained, so it's a whole different animal. As we discussed, I literally got the impression from Oil Forum that 5W-20 was fine; even 0W-20. "I even thought about putting the Redland 0W-20 in here for the winter since that one is a 2.9cP or cSt, my memory fails me, and is virtually a thin 30.."

If I really, didn't care about it, I wouldn't have shared it. Did you all notice all my new tools?
- place to put those tools?
- use of those tools?
- tools strewn around amid Honda and other Chevy tear-down, just waiting to be used?

This isn't street-side in Newark, where all my car endeavors, be they good or bad, get rewarded with my ride stolen.................

We have AEHAAS putting FoMoCo Motorcraft 5W-20 in a Murcielago, and folks give him hi-5 on his oil choice.. I'm not a hater but I also put in a 5W-20.. it's not like it doesn't come up frequently, "Can I use 5W-20 where it says 5w30?"

So.. I could still change it out, sure. All I'm saying is that it's going to be changed out in a month or so, anyways. "For the winter." Since our mechanic is another one of these crazy folks that has selective "I can't read" when it comes to oil cap. I don't get too mad, since it seems to be a common affliction we share
smirk.gif
 
Originally Posted By: InfmousCornholio

We have AEHAAS putting FoMoCo Motorcraft 5W-20 in a Murcielago, and folks give him hi-5 on his oil choice..


Ali isn't getting "high 5's", it is more like people just watch and see if anything happens. He also BABIES those cars, so oil temps do not get high (the opposite of how you drive). And keep in mind, he is incredibly wealthy, so if he wants to experiment with non-spec oils in a car like a Murcielago, and he DOES nuke the engine, he can afford to replace it.
 
Oh, that poor, poor GMC!
cry.gif
I bet after all of that "by the book" maintenance it's had all of its life, it never saw this coming!

Cue "Taps" in its honor.
 
Originally Posted By: OVERKILL
Originally Posted By: InfmousCornholio

We have AEHAAS putting FoMoCo Motorcraft 5W-20 in a Murcielago, and folks give him hi-5 on his oil choice..


Ali isn't getting "high 5's", it is more like people just watch and see if anything happens. He also BABIES those cars, so oil temps do not get high (the opposite of how you drive). And keep in mind, he is incredibly wealthy, so if he wants to experiment with non-spec oils in a car like a Murcielago, and he DOES nuke the engine, he can afford to replace it.


And my other points? Out of my reply.. you quoted my reference to AEHaas. Ok. My other tenets and points? Those? ..

Yeah, he babies performance-built niche super high end Italian speed machine, infuses with Audio DNA as of late in Miami heat.. I do not remember the exact thread number or URL, but at least one told him it was a "good choice." Also, 0W-20 was suggested.

And let us not get started on Mobil 1 0W-20 - or even 5W-20 - that could be said is fine..

At least one poster on here has said that M1 0W-×0, I'm a Dodge Ram, TOWING, long highway trips, didn't use a drop...

You're not NOT making sense, but, I think we are way, waaaay overboard on doom predictions with this.

GMC feels much more responsive on its new Magnatec fill, and the other two.. are coming along. IT'S THAT SIMPLE!

Was the 10W-40 "better?" Let's see what other BITOG things we can flip around. For yours truly.....
 
Originally Posted By: threeputtpar
Oh, that poor, poor GMC!
cry.gif
I bet after all of that "by the book" maintenance it's had all of its life, it never saw this coming!

Cue "Taps" in its honor.


You are correct.. it had "by the book" services, with 10W-40 after it left dealer care...

Now, Enter The GHT.

No ghetto here................ and this will make ALL THE difference.
 
Originally Posted By: InfmousCornholio


Now, Enter The GHT.

No ghetto here................ and this will make ALL THE difference.


Like this for example. What does this mean? That the truck was maintained well and runs ok, but now you are taking over and things will be different?
 
As long as you're not towing or off roading with it, I don't see a problem. It will start cooling down soon and you will be fine.

Heck, I ran 5w-20 in my Jeep 4.0 once. It was quite quiet on it (still had it's usual knock - but didn't get worse). 18PSI hot idle. Same as a 5w30.

With those miles on it, I would probably stick to cheap 5w30 from Walmart.
 
Personally I think using 5w20 is the least of that vehicles problems.

Do you really think it will matter to the longevity of that vehicle. That old oil color looked like some water is mixing is going to kill the motor long before a slight variance in oil pressure theory on a worn GM engine.
 
Originally Posted By: InfmousCornholio
Ever think that I got sick of making engines rod knock with MMO hijijx and shenanigans? This vehicle has been maintained,

If this vehicle has been maintained, then why did you think it needed all those wizards in a bottle and a gallon of water?
 
Originally Posted By: Quattro Pete
Originally Posted By: InfmousCornholio
Ever think that I got sick of making engines rod knock with MMO hijijx and shenanigans? This vehicle has been maintained,

If this vehicle has been maintained, then why did you think it needed all those wizards in a bottle and a gallon of water?


Exactly.

Bzzzzzt! Try again!
 
Status
Not open for further replies.

Similar threads

Y
VQ37VHR Motor bogging down at cold start; oil related?
Replies
18
Views
406
Hall
Hohn
Oil Filter Relocation for convenience and performance
2 3
Replies
46
Views
3K
Donald
D
Advice on what to do about a technician who stripped my spark plugs into the head
2 3 4
Replies
66
Views
5K
thastinger
tired
Help with recommendation for motor oil for Toyota and Nissan daily drivers
2 3
Replies
54
Views
5K
tired
A
My Skyactive 2.5L Piston Soak Story ... and the Comedy of Errors...
2
Replies
38
Views
5K
AdmiralYoda
Back
Top Bottom