Update: 5W-30 & Heavier Recommended RoTW (31 Viewers)

[xeuxaz]

LSJr. usually posts good stuff. He can't keep up with this one though.

iirc, GM withdrew this recommendation less than 4 days after issuing the increased viscosity recommendation. That whole engine lineup seems to be fundamentally designed with issues related to what they're trying to limp across the powertrain line with increased viscosity. Too bad too, as the over complicated nature of cylinder deactivation, etc makes these already complex engines even more so.

It doesn’t look like it was withdrawn; there’s even a note about replacing the oil cap and an addendum to the manual. Interestingly, GM recommended 5W30 for this engine in other markets, while in the U.S., they specified 0W20. (That part immediately reminded me of this thread.)

https://static.nhtsa.gov/odi/rcl/2025/RCRIT-25V274-6343.pdf

 

[gasman4u]

It doesn’t look like it was withdrawn; there’s even a note about replacing the oil cap and an addendum to the manual. Interestingly, GM recommended 5W30 for this engine in other markets, while in the U.S., they specified 0W20. (That part immediately reminded me of this thread.)

https://static.nhtsa.gov/odi/rcl/2025/RCRIT-25V274-6343.pdf

You're right. Looks like the EPA/CAFE team stepped up and announced approval for this engine was based on 0W20 oil spec and not another weight to GM. I'd venture they would face fines, etc if not going back to 0W20 in "unaffected engines." This is going to yield results and ownership experiences that mirror those of the 3.5L tundra fiasco IMO. I know I wouldn't be happy were I in this cadre of affected vehicles. Stay tuned for the VIN catchment to widen and include more and more owners who need new engines well within the powertrain warranty. Or worst case, those will need new engines at just over the mark of whatever they cover on the powertrain warranty. Even if I wasn't in whatever they're decreeing is the list of included VINs, I'd sure as hell run something thicker than 0w20 for the increased viscosity to hopefully mitigate their engineering shortcomings.

Latest I've seen is speculation about manufacturing issues with crankshaft polishing from the factory being inadequate. Who knows?

EDIT: I cannot confirm, but supposedly a LOT of dealerships ran out of 0W40 within the first few days of this TSB/RECALL/ETC being released. Again, this is anecdotal but thought it was relevant in what GM is saying/doing now vs what may or may not be what needs to be done to remedy the root cause.

 

[skrypj]

lol GM is a joke of a company. Crawl underneath any one of their cars and trucks and see how much quality and durability they cut from their designs.

I believe GM's engineering is quite strong, their weakness has always been the management.

 

[skrypj]

You're right. Looks like the EPA/CAFE team stepped up and announced approval for this engine was based on 0W20 oil spec and not another weight to GM. I'd venture they would face fines, etc if not going back to 0W20 in "unaffected engines." This is going to yield results and ownership experiences that mirror those of the 3.5L tundra fiasco IMO. I know I wouldn't be happy were I in this cadre of affected vehicles. Stay tuned for the VIN catchment to widen and include more and more owners who need new engines well within the powertrain warranty. Or worst case, those will need new engines at just over the mark of whatever they cover on the powertrain warranty. Even if I wasn't in whatever they're decreeing is the list of included VINs, I'd sure as hell run something thicker than 0w20 for the increased viscosity to hopefully mitigate their engineering shortcomings.

Latest I've seen is speculation about manufacturing issues with crankshaft polishing from the factory being inadequate. Who knows?

EDIT: I cannot confirm, but supposedly a LOT of dealerships ran out of 0W40 within the first few days of this TSB/RECALL/ETC being released. Again, this is anecdotal but thought it was relevant in what GM is saying/doing now vs what may or may not be what needs to be done to remedy the root cause.

My understanding is there is now a class action lawsuit against GM because the 0W-40 will result in lower fuel economy than the 0W-20

Could throw reduced HP and torque in there too.

 

[gasman4u]

My understanding is there is now a class action lawsuit against GM because the 0W-40 will result in lower fuel economy than the 0W-20

Could throw reduced HP and torque in there too.

I saw some of that mentioned elsewhere, but I hope it's fake! IF TRUE, it's ridiculous IMO.

 

[FrazzledHunter]

I saw some of that mentioned elsewhere, but I hope it's fake! IF TRUE, it's ridiculous IMO.

It's stuff like this and my experience with GM products that make it #1 on my list of car brands to avoid. #2 & #3 are Ford and Chrysler*.

*Does Chrysler even make cars anymore?

 

[gasman4u]

It's stuff like this and my experience with GM products that make it #1 on my list of car brands to avoid. #2 & #3 are Ford and Chrysler*.

*Does Chrysler even make cars anymore?

Yikes. I’m of the mind to avoid anything Korean for now.

 

[Artie]

Yikes. I’m of the mind to avoid anything Korean for now.

It seems like most all makes have issues these days, some are a couple models, others are across the board. I believe luck plays as much of a role as does a good maintenance history.

 

[04UZJ100]

I believe GM's engineering is quite strong, their weakness has always been the management.

lol wut?

 

[TeCKis300]

lol wut?

Thought it was just me as a spat out my coffee when I read it. An organization of mediocrity across the board.

I kid, should give credit to the GM bean counters.

 

[gasman4u]

Thought it was just me as a spat out my coffee when I read it. An organization of mediocrity across the board.

I kid, should give credit to the GM bean counters.

lol wut?

I do wonder how much institutional rot their poor executive leadership currently steers towards immediate short term stock bumps vs strategic milestones. Self vs company long term interest is what I’m driving at. They sure look to be taking a page from general electric’s book on “how to sink an iconic worldwide brand for dummies” with their dogsh*t decision process and execution of new cars.

I miss the reliable V8’s of yore from GM. Were they perfect? Absolutely not. But my God, they built the following the current “leadership” is scalping.

 

[Zill]

I do wonder how much institutional rot their poor executive leadership currently steers towards immediate short term stock bumps vs strategic milestones. Self vs company long term interest is what I’m driving at. They sure look to be taking a page from general electric’s book on “how to sink an iconic worldwide brand for dummies” with their dogsh*t decision process and execution of new cars.

I miss the reliable V8’s of yore from GM. Were they perfect? Absolutely not. But my God, they built the following the current “leadership” is scalping.

Much could be said about the current state of affairs with Toyota

 

[skrypj]

lol wut?

Thought it was just me as a spat out my coffee when I read it. An organization of mediocrity across the board.

I kid, should give credit to the GM bean counters.

Sorry I’m not a koolaid drinking Toyota fanboi 24/7 . You sure it wasn’t koolaid you spit out?

GM does do some great stuff if you can put the cup down for a second.

 

[TeCKis300]

Sorry I’m not a koolaid drinking Toyota fanboi 24/7 . You sure it wasn’t koolaid you spit out?

GM does do some great stuff if you can put the cup down for a second.

To @Zill 's point, Toyota has lost me as a new car customer. Porsche is almost there too. GM lost their way well over a decade ago. I'm not drinking anything but sure sounds like someone is as that hit a sore spot.

Frankly, all the legacy car makers have rested on their laurels for far too long and are getting their lunch eaten.

 

[bloc]

So... 0w-40 in the 3UR? Generally designed for Euro cars, IIRC.

If so, are there nuances to additives that the euros like that toyota isn't fond of? From my diesel 4runner days I remember something about significant differences in how the valve buckets were designed meaning long-term the 1KZ-TE didn't like the direction american diesel oil formulations were going. Calcium, something or other.

But no clue if that was really accurate..

Edit: same question, 5w-40.. which is generally designed for diesels? (with very specific requirements - and therefore possibly compromises - to protect their sensitive emissions systems.. stuff that wouldn't apply to us)

 

[gasman4u]

So... 0w-40 in the 3UR? Generally designed for Euro cars, IIRC.

If so, are there nuances to additives that the euros like that toyota isn't fond of? From my diesel 4runner days I remember something about significant differences in how the valve buckets were designed meaning long-term the 1KZ-TE didn't like the direction american diesel oil formulations were going. Calcium, something or other.

But no clue if that was really accurate..

Edit: same question, 5w-40.. which is generally designed for diesels? (with very specific requirements - and therefore possibly compromises - to protect their sensitive emissions systems.. stuff that wouldn't apply to us)

BLUF: You're right and you don't want to run Shell diesel Rotella, etc in your gas engine.

If your 5W40 question is regarding HDEO (diesel engine oil), yes - you don't want to use that for a gasoline engine as you wouldn't want to use any gasoline engine formulation for a diesel. IIRC, a big part is due to soot mitigation in diesel oil and its formulation specifically to combat this. There's something it lacks that gasoline engine oils contain in the additive packs. I know - I'm doing a terrible job in explaining but it's been a while since I read about the "why" behind this. I hate to keep pointing to this guy (motor oil geek Lake Speed Jr), but he's got the best concise messaging on YT I've seen from a legitimate and reliable source that's easy to find. He does a much better job in explaining than I do.

There's another forum dedicated to however deep you want to dive into oils, oil analysis, etc. I spend some time there, but my eyes start to cross after a while.

EDIT: Some things that I am not sure have been mentioned previously are better heat transfer with thinner oils, more HP with thinner oils, and better heat mitigation with full synthetic oil. So it's not ALL bad with thinner oils.

 

[bloc]

EDIT: Some things that I am not sure have been mentioned previously are better heat transfer with thinner oils, more HP with thinner oils, and better heat mitigation with full synthetic oil. So it's not ALL bad with thinner oils.

Thanks for the recs. And yes I do remember reading that the 10w-60 required in BMW's S65 took forever to reject heat, once the temp was raised. I think the context was track work though.. I'm suddenly finding myself slightly more disappointed Mr. T didn't give us the factory option to monitor oil temp even in the advanced PIDs.

I'm trying to think through when this could be an issue for us. Our contexts for elevated oil temps would probably be towing, and maybe low-speed crawling. Anything I'm not thinking about? Towing is a case where oil performance is very important.. would the ability to get heat out of the oil quickly matter much? For crawling.. seems like you'd be fine (with hot oil) until you have to cane it for some reason.

(All of this keeping in mind our engines are pretty easy on oil in the first place)

Edit: just now realizing it's not just getting thermal energy out of the oil, it's the oil's ability to get thermal energy out of the engine. So.. toyota says 15w-40 and 20w-50 are options depending on climate, but going that far still may not be a good idea. I'll start looking into hot viscosity specs)

 

[gasman4u]

Thanks for the recs. And yes I do remember reading that the 10w-60 required in BMW's S65 took forever to reject heat, once the temp was raised. I think the context was track work though.. I'm suddenly finding myself slightly more disappointed Mr. T didn't give us the factory option to monitor oil temp even in the advanced PIDs.

I'm trying to think through when this could be an issue for us. Our contexts for elevated oil temps would probably be towing, and maybe low-speed crawling. Anything I'm not thinking about? Towing is a case where oil performance is very important.. would the ability to get heat out of the oil quickly matter much? For crawling.. seems like you'd be fine (with hot oil) until you have to cane it for some reason.

(All of this keeping in mind our engines are pretty easy on oil in the first place)

It's getting beyond my wheelhouse in understanding to make any solid recommendations other than to say there's no "one size fits all" for our engines and use case should definitely be considered when making the choice on what weight you want to run. The cSt of your specific oils should be considered IMHO as even within grades there are oils that are thicker vs thinner amongst the (insert oil weight here). I'm going to speculate and try to make what I'm thinking make sense with the following:

Assuming quality oil with a good additive pack, my impression is that thicker oil viscosity index improvers can handle shear better than thinner (at the bearings), especially when hot (the only consideration I have to offer with the crawling example above). This could be helpful (I'm thinking) when on the trail and having to use a bit more throttle than nuance with steering input. I'd imagine an oil slightly thicker than the 0w20 spec would prove beneficial for most of us who use these rigs on the trail, towing, or with high throttle input besides from starting at a stop sign/light. I'm no SME - just a guy who reads and is interested in learning the "why" behind the "what." Feel free to chime in and offer differing/alternative/reinforcing input as I am always interested to know what makes people choose what oil, even if it's not something I'd go for. HTH

 

[Mingus Dew]

This is a fascinating thread to read through. I never thought much about motor oil but it makes sense that there is such a nuanced science to it.

Seems like living in South Florida (frequently gets above 100 in the summers these days and rarely gets below 50 in the winters), I'd benefit from a slightly heavier oil like 5w30 or even 0w40 or 5w40?

I may switch to 5w30 on the next oil change and see what I notice.

 

[xeuxaz]

This is a fascinating thread to read through. I never thought much about motor oil but it makes sense that there is such a nuanced science to it.

Seems like living in South Florida (frequently gets above 100 in the summers these days and rarely gets below 50 in the winters), I'd benefit from a slightly heavier oil like 5w30 or even 0w40 or 5w40?

I may switch to 5w30 on the next oil change and see what I notice.

It's a good call to move to 5w30 with ambient temps that high. You'll notice a quieter engine and a slight pressure bump. (I'm in Phoenix and it was a simple win for my 3UR trucks)