Why does the 4.3l use 5w-30 oil and the 5.3l use 0w-20?

Jayselectricco · October 12, 2022

From my understanding the 4.3l ecotec is pretty much the same as the 5.3l ecotec minus 2 cyl. So why are they listed using different oil weights?

Grumpy Bear · October 12, 2022

Why indeed

The question you are asking is a question of motive and could only be answered by those who provided the specifications for each. You won't get a straight answer or a truthful one.

Would it be fruitful to speculate, contemplate, guess, hypothesize, reflect, ruminate, surmise, weigh or wonder? :dunno:

Motive questions are a flailing at the wind sir. A more pointed and useful question maybe easier to answer from someone whose motives you are surer about. Yours! Perhaps, why does the matter to me? What am I trying to learn?

I can't read your mind, but this question gets asked allot by one of two groups.... mainly. Those looking for ' best wear protection' OR those looking for 'best fuel efficiency'. Those are questions that can be answered a bit more straight forward without doubt of personal motivations in the reply.

This will be ignored, and the party will now begin.....

:lurk:

Edited January 4, 2023 by Grumpy Bear
gramar and spelling

Jayselectricco · October 12, 2022

Ok, well I had a problem with P06DD which turned out to be my thermostat stuck was the main problem. It was never getting to temperature so the computer was holding it in "high oil pressure mode" to try to warm the engine up. Well I also had a worn PCV valve which was causing my oil to get dirty faster than normal which also triggers the code because it sees dirty oil as "the wrong viscosity." So I was going about 2k miles after an oil change with no code, then the oil was getting dirty and popping up that code. I would change my oil and be good for another 2k miles until the code returned again. I changed the the PCV valve and could tell a big difference. The first time after I replaced the PCV valve the oil got even dirtier, however thinking logically I assumed that since it was "breathing" as it should now that it was cleaning sludge out of the engine. Haven't had the problem again since then, but I change my oil at 3K miles. I have been talking to others that have had this same code and sharing my experience with them, and have come across others that get this code right before oil change, and they change the oil and everything is good until close to the next one. I wonder if Chevy didn't change the programming in the 4.3 to look for 5w-30 oil viscosity and it is looking for 0-w20 viscosity, and when 5w-30 gets dirty it is going out of tolerance, when if it were looking for 5w-30 it would still be in tolerance?

Edited October 12, 2022 by Jayselectricco

diyer2 · October 12, 2022

My 2012 5.3 requires 5W30. I think you're overthinking this.

Jayselectricco · October 12, 2022

I know what you mean, they just totally redone the 5.3 and 4.3 in 2014 and I think they made the tolerances a lot tighter.

Edited October 12, 2022 by Jayselectricco

newdude · October 12, 2022

Fuel economy is the biggest driver IMO. GM builds mostly 5.3 and 6.2 trucks, and they had a target to get these trucks over 22mpg which until the EPA kept changing their ratings procedure, they did. When you build a lot of big V8s, you need as much fuel efficiency out of every nook and cranny possible. That's why its 75w85 in the rear diffs, all terrain tires only by description as such but its an all season (the infamous Goodyear Wrangler Fortitude HT that GM called an AT).

Where this angle gets interesting is the new T1 trucks have the same or lower ratings from the EPA as the K2. However, they are larger trucks and likely bumped up their CAFE footprint which is a loophole the OEs use all the time to help offset.

Now look at this as well. Camaro with the LT1 uses 5w30 (and now 0w40) in the 6.2. 5w30 met GM's need for all uses of Camaro except for track. Track use they wanted 15w50. They then changed to 0w40 Dexos2 which Dexos2 is low ash spec oils so you can have an oil that is both track and road worthy that won't harm the catalysts.

diyer2 · October 12, 2022

So the answer is use 5W30 and change it when needed.

Jayselectricco · October 12, 2022

I guess what I am really asking here is do you think it would hurt anything to try 0w-20 just for these guys to see if it made it less prone to throw the code near oil change time? Or would changing to a different weight oil hurt the AFM?

diyer2 · October 12, 2022

You will only know if you try it.

pokismoki · October 12, 2022

15 minutes ago, Jayselectricco said:

I guess what I am really asking here is do you think it would hurt anything to try 0w-20 just for these guys to see if it made it less prone to throw the code near oil change time? Or would changing to a different weight oil hurt the AFM?

take a poll of those who have the most engine failure using either 0w-20 watered down oil or 5-30 or 10-30 oil

Jayselectricco · October 12, 2022

I absolutely agree that 5W-30 is better at protecting engines... my thought is this... since the 4.3 and 5.3 are pretty much the same except ones a 6 cyl and ones an 8, that they knew the 6cyl would get the gas mileage no problem but the 5.3 needed 0w-20 to achieve the number it needed.

customboss · October 12, 2022

If I had to guess 0w20 was indicated for newer 5.3's for more stable hydraulic reliability for AFM. The delta in HTHS or wear protection from 5w30 to 0w20 is negligible in the 5.3 design. But the 5w30 will drive a higher hydraulic pressure thats not needed and can change valve timing dynamically. GM has had issues with off the shelf API oil volatility and vis stability for hydraulic reasons nothing else. Thus the Dexos spec. If you run a good synthetic oil it won't matter much becasue they will be super stable vs off the shelf lower quality barely meeting API spec oils. Just an opinion.

Jayselectricco · October 12, 2022

11 minutes ago, customboss said:

If I had to guess 0w20 was indicated for newer 5.3's for more stable hydraulic reliability for AFM. The delta in HTHS or wear protection from 5w30 to 0w20 is negligible in the 5.3 design. But the 5w30 will drive a higher hydraulic pressure thats not needed and can change valve timing dynamically. GM has had issues with off the shelf API oil volatility and vis stability for hydraulic reasons nothing else. Thus the Dexos spec. If you run a good synthetic oil it won't matter much becasue they will be super stable vs off the shelf lower quality barely meeting API spec oils. Just an opinion.

That makes sense, however the 4.3 has the AFM too so why wasn't it made to use the 0w20 as well?

LDM · October 12, 2022

The answer is very simple. CAFE. Nothing else. I've ran 5W30 in my 2018 since I got it. No issues at all.

newdude · October 12, 2022

2 hours ago, Jayselectricco said:

I guess what I am really asking here is do you think it would hurt anything to try 0w-20 just for these guys to see if it made it less prone to throw the code near oil change time? Or would changing to a different weight oil hurt the AFM?

4.3 calls for 5w30, use 5w30. No point in running 0w20 in it. P06DD comes back its going to need an oil pump as its the same solenoid issue with the pump the V8s have.

1 hour ago, customboss said:

If I had to guess 0w20 was indicated for newer 5.3's for more stable hydraulic reliability for AFM. The delta in HTHS or wear protection from 5w30 to 0w20 is negligible in the 5.3 design. But the 5w30 will drive a higher hydraulic pressure thats not needed and can change valve timing dynamically. GM has had issues with off the shelf API oil volatility and vis stability for hydraulic reasons nothing else. Thus the Dexos spec. If you run a good synthetic oil it won't matter much becasue they will be super stable vs off the shelf lower quality barely meeting API spec oils. Just an opinion.

I would agree, however, GM had a PI in their service manual for oil aeration leading to lifter failures on the Gen V 5.3 and 6.2 which use...? 0w20. Conveniently this PI disappeared from the service manual (funny isn't it?)

Camaro and Corvette have far less reports of AFM lifter failure aside from the known production window late 2020-early 2021. Plus the older LS engines on 5w30 tended to run higher mileage before encountering a lifter failure.