5w-30 too thick for modern cars?

[edhackett]

I just never realized 5w-30 would be worse than 0w-20

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Which one of those 20 grade oils was too thick and causing your problem?

Ed

 

[demarpaint]

No, this horse has been beaten to death more times than I can count.

 

[4wd]

Is 5w-30 too thick for modern cars?

So I recently purchased a 2019 Lexus is350.
It has a 2GR-FKS V6 in it.
Obviously the factory calls out for a 0w-20 oil.
Dealer had new 0w-20 in it, so after 5K miles, I swapped to 5w-30.
I figured running Mobil 1 Extended Performance 5w30 oil was fine since the early 2010s 2GR listed 5w-30 as the recommended oil.
I've run that 5w-30 EP oil in many cars that went above 300,000+ miles.

Within a day, the engine was running oddly.
The exhaust tone on mid throttle sounded weird. Kinda like a drone.
I thought it was leaking exhaust gaskets, but I changed them to no avail.

My brother had mentioned that some modern cam phasers don't like thicker oils. And since it's 50F out, I thought maybe the oil just wasn't flowing right.
So I used an OBD2 scanner to see what the cam angles were.
And sure enough, the cam timing was kind of erratic and laggy.

So I changed the oil to a Mobil 1 Extended Performance 0w20 and the issues are all gone.
No weird noises
Cam timing is consistent
And the car feels more responsive.

I always thought the difference between 0w-20 and 5W30 oil was minimal or non existent.
Apparently not

No - all in signature came with 0W-20

 

[SC Maintenance]

If you do a search AI will tell you that thicker oil can mess up your VVT and you need to use OEM spec'd weight.

Likely due to threads like this here and elsewhere being sucked into the borg.

Just goes to show how not ready the public LLM's are for primetime.

 

[JavierH19]

I think OP is trolling us. This is for the non-us manual where they don't have to put up with cafe regulations which I have talked about and have posted the EPA document that they have sent to manufacturers which gave them guidance on how to rate oils and what is and is not in compliance and have gone through it. I'll try to find it to post here. This horse has been beaten to death.

Post in thread '0W-8 in 2026 Toyota Prius' https://bobistheoilguy.com/forums/threads/0w-8-in-2026-toyota-prius.399814/post-7370438

 

[rijndael]

Just goes to show how not ready the public LLM's are for primetime.

As more people rely on AI/Google/Etc for basic knowledge, this will get worse because there will be fewer people with actual knowledge to call BS.

 

[rstsco]

Suggest watching these videos if you want to understand viscosity in auto engines and the effects of changing it. The second video is recommended by Jason in the first video. The third video is a very well done AI generated. If not for a few mispronunciations, it'd be tough to know it was't a human reading a script. Good info on ACEA standards vs EPA standards.

 

[Wireman1987]

This forum needs some AI to detect a viscosity thread starting troll.

 

[dnewton3]

I have a 2013 ES350 (2GR-FE).
I have a 2016 RX350 (2GR-FKS).
I had a 2023 ES350 (2GR-FKS).

I have experimented with various lubes in those vehicles, using 0w-20, 5w-20 and 5w-30. I can find no data-driven distinguishable difference in them in terms of wear data. I cannot fathom how such minor differences in viscosity are somehow going to affect bearings, phasers, etc.

Is a 20 grade too thin for most modern gas engines? No.
Is a 30 grade too thick for most modern gas engines? No.

As for the engine sounds, etc ... It's the placebo effect, IMO.


NOTE: I'm excluding extreme performance vehicles, etc from my comments.

 

[SC Maintenance]

I will add - since were back into intelligent discussion

If by some chance your ECU could not get the VVT to move to where it wanted to - remember the cam sensor measures the actual angle and reports back - then you would get a code - I believe P0011 is cam too retarded and P0012 cam too advanced, or maybe I have those backwards. Either way, it doesn't take much. Nissan VQ's have this problem when the gallery gaskets start leaking a tiny amount.

 

[rstsco]

I will add - since were back into intelligent discussion

Here we go again with the irrational claims.

 

[Rat407]

I'll just toss out there that GM recently shot all the way up to 0w40 for a large population of VVT V8's that already had problematic lifters.

It's my understanding that they only did this to the 6.2 engines that have connecting rods that were machined out of tolerance. 2022-2024 model year only. Everything else still gets 0w-20. I'm sure if they didn't need to show mpg numbers for CAFE, they would use 0w-40 in everything. More money for them on oil changes.

 

[Johnny248]

Is 5w-30 too thick for modern cars?

So I recently purchased a 2019 Lexus is350.
It has a 2GR-FKS V6 in it.

I have a 2GR-FKS Taco that I've been running 5w30 in. Zero issues.

 

[kschachn]

Could you post the lab results for us?
My test above didn't show any difference in wear from 0w-20 to 5w-30.

Another gross misconception to accompany this beat-to-death topic. A $30 spectrographic analysis does not compare oil wear between two oils. Blackstone themselves has stated that no oil they have tested gives a statistically different result. It's not the tool, it's not the right test environment. Comparative wear testing between oils is expensive and far more complicated. For a reason.

 

[barkingspider]

Went from 0w20 to 5w30 in my “modern” 2024 Lexus GX550, no issues here. It runs like normal

 

[kschachn]

I don't have a way to record OBD2 data history with the cheap reader I use
Maybe the $2,000+ code reders can do that.
But a guy that I work with used to be a master Toyota technician.
He said that thicker 10w-30 oils can sometimes interfere with VVT systems or variable cam lift stuff.
He said the earlier hybrids were very particular about using thinner oils.

I doubt the oils were left in too long.
Here's the oil test from the dealer 0w-20 and the Mobil 1 Extended Performance 5w30.
lowwr of equal to what Blackstone usually sees in 2GR

I just never realized 5w-30 would be worse than 0w-20

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You have no idea what you are talking about here. You're way out of your wheelhouse in terms of what's required for such a test or about how oils behave.

 

[fen1]

Please explain to me how a slightly thicker oil changes how a cam phaser operates? I will wait.

You're going to be waiting a l o n g time.

 

[altaylar]

Praising 0w20 is sort of a taboo around here. You clearly had an issue that was solved via an oil change to a lower viscosity.

While I agree with most here that what solved your issue is almost certainly not the change in viscosity but something else going on in there, it would really be an educational topic if we tried to find what that was, rather than outright dismissal and deregatory remarks.

 

[altaylar]

By the way i am not familiar with your engine and i know there are members here that have the exact same vehicle, but i am aware of an instance where Redline's XW30 oil might have led to a P0011 error on a 1.5 GM turbo engine. The vehicle had a tune on it, so so that is an additional variable, but it had Pennzoil Ultra Platinum 5w20 before that it was happy with. After the tune it got redline, and then changed to Molygen 5w30 and had no issues.

If you ask me, 1-2 grade thicker oil should not cause any issues like that, but that is just an additional data point. Perhaps a small fraction of engines have certain level of manufacturing error with the surface finish or dimension that makes them more susceptible to oil thickness. That could explain why most people (including me) run thicker oil and are just fine, but some people receive errors.

 

[4wd]

It's my understanding that they only did this to the 6.2 engines that have connecting rods that were machined out of tolerance. 2022-2024 model year only. Everything else still gets 0w-20. I'm sure if they didn't need to show mpg numbers for CAFE, they would use 0w-40 in everything. More money for them on oil changes.

Or cranks from