Why Do Knowledgeable Folks on Here use 20 wt Oil

[Al]

Whenever “Why use 20wt oil” discussion pops up, I like to tell people actual proof that 20wt oils are more than adequate for regular driving with a reasonable oci.

I’ve been on Bitog only for a couple years now, and yes I’ve read my posts on how thicker oils are better. But my argument is, how much better is it, if my 3.5 Ecoboost has been perfectly fine with 20wt for the past 120k miles, along with millions of other cars on the road?

With 20 wt. you have no cushion. My Subaru made it to 270 K miles on the heavier oil. It used 30 wt. Eventually it needed 40 wt bc of oil consumption. There is every reason to believe if the vehicle had gotten 40 wt. it would never needed to switch from the "thinner" oil.

So yes 20 wt is "adequate" but not best. When the testing in pre 2000 vehicles attempted to "certify" if a vehicle could obtain 175K (I believe) engine they discovered it could not. They ad to reduce the projected engine live to I believe 150 K miles. Subsequently the engines were redesigned.

Lubrication engineering indicates that a heavier oil will deliver less bearing stress (Three factor Graph).

My cars are speced for 20 weight oil, but I use 5W-30 due to it's higher HTHS.
Extra protection at no additional cost. Whats not to like?

This

 

[hk24]

Both those oils are perfectly fine.

Good. I bought the Supertech...

 

[Triple_Se7en]

2010 Hyundai Santa Fe 2.4 thetta 2 with 200k on od. Always have uses m1 5w-20 and have had no consumption between oci

Yours is a Gen 1 engine. They all seemed to run for 150-200k and beyond miles.
The Next-Gen from 2012-2019 are the 2.4 primary problem-child engines.

 

[Auto tech]

Yours is a Gen 1 engine. They all seemed to run for 150-200k and beyond miles.
The Next-Gen from 2012-2019 are the 2.4 primary problem-child engines.

Correct. The Latter versions are gdi. Nonetheless it still is a thetta 2

 

[Astro_Guy]

I have a 2016 Honda Accord with the 2.4 liter four that is spec'd for 0w-20 but sees only 5w or 0w-30. I also have a 2017 Toyota Prius V spec'd for 0w-20 where I am considering using 0w-16. So what does that make me? Indecisive? Insightful? Maybe a bit cerebral? What it doesn't make me is a foot soldier in the thick vs. thin war.

It's all about the use case. The Honda is a fuel diluter and can benefit from the thicker oil. The Toyota is basically a grocery getter with an engine specified for 0w-16 in later years. I don't believe in a universal answer to the thick vs. thin question and nor should any of you. Drop some coin on a UOA. Opinions without data are basically meaningless.

 

[hk24]

I have a 2016 Honda Accord with the 2.4 liter four that is spec'd for 0w-20 but sees only 5w or 0w-30. I also have a 2017 Toyota Prius V spec'd for 0w-20 where I am considering using 0w-16. So what does that make me? Indecisive? Insightful? Maybe a bit cerebral? What it doesn't make me is a foot soldier in the thick vs. thin war.

It's all about the use case. The Honda is a fuel diluter and can benefit from the thicker oil. The Toyota is basically a grocery getter with an engine specified for 0w-16 in later years. I don't believe in a universal answer to the thick vs. thin question and nor should any of you. Drop some coin on a UOA. Opinions without data are basically meaningless.

Honda recommends 0W20 - and maybe 5W20 in a pinch or in V6 models. Deviating from that.... is that wise?

 

[kschachn]

Honda recommends 0W20 - and maybe 5W20 in a pinch or in V6 models. Deviating from that.... is that wise?

Yes.

 

[Astro_Guy]

Honda recommends 0W20 - and maybe 5W20 in a pinch or in V6 models. Deviating from that.... is that wise?

Based upon the multiple UOAs I have for this vehicle using both 0w-20 and 5w-30 I believe that it is.

 

[tolian21]

Honda recommends 0W20 - and maybe 5W20 in a pinch or in V6 models. Deviating from that.... is that wise?

Maybe honda recommends 0w-20 in US, but in Mexico there are other recommendations.
I guessed you missed the point in this thread that some newer engines are fuel diluters and will make your 0w-20 look like 0w-10

 

[ARCOgraphite]

My cars are speced for 20 weight oil, but I use 5W-30 due to it's higher HTHS.
Extra protection at no additional cost. Whats not to like?

Dimestore 5W30 is a dirty light constituent oil laden with VM goo. The reason so many are using VR&P and HPL no VM (Vii to some)
to clean up gummed up and possibly engine destroying pistons.

Many here can't get it through their head that a commodity class Multigrade oil is always a compromise

 

[Triple_Se7en]

Maybe honda recommends 0w-20 in US, but in Mexico there are other recommendations.
I guessed you missed the point in this thread that some newer engines are fuel diluters and will make your 0w-20 look like 0w-10

Exactly
Plus, data oly reference things like how the hypothetical 0w20 oil was built (for example).

So that 'specific' data that we are reading is what's best for both the 6.0 V8 and that 1.2 three cylinder? What is the percentage that the data will be correct in your specific instance?....... 25%?.... 50%?...... 75%?....100%?...... I seriously doubt it.

The best oil data is you listening to your engine, eyeballing the used oil, reading UOAs and driving your machine to witness how it reacts to all this data. How smooth it responds under slow city manuevers about town and along the highways at much higher speeds. The oil data has no idea if you're going to use this oil for 3k, 10k or 20k...... etc....etc....etc.

It's not about X's and O's on paper. It's not about the numbers 1 thru infinity. Your particular engine may prefer HPL over Supertech.... or it may prefer just the exact opposite. Your engine will eventually tell you if the data you are holding in your hand is either vastly underrated or vastly overrated. It's impossible for that data to render a decision that that piece of data in your hand is what's best for that 1.2 and that 6.0.

 

[RDY4WAR]

Honda recommends 0W-20 for CAFE reasons. It's a compromise much like everything else on the car. A higher (dynamic) viscosity will offer more protection by way of a thicker oil film. However, you can't subtract from zero. If a 0W-20 is providing sufficient film thickness to maintain full hydrodynamic lubrication, then going to a 0W-30 or 5W-30 will offer no benefit outside of headroom. To quote Vin Diesel here "doesn't matter if it's an inch or a mile." No contact is still no contact.

The most likely case is an engine with tighter bearing clearance (.0014-.0018"), warranting a 0W-20 or 0W-16 oil, will still have the same dynamic viscosity with a 5W-30 than a 0W-20. The increased hydrodynamic friction, combined with slower oil flow through the bearing, means the oil and bearing will run hotter, and thus that 5W-30 gets thinned down to likely close to the same viscosity as the 0W-20 anyway. We're splitting hairs here in terms of a commuter vehicle where the biggest problem you'd likely encounter is a slight loss in fuel efficiency.

To take an extreme example of where such as this would be more felt, let's look at a NASCAR engine. The bearing clearance is ~.0016" rods and ~.0020" mains. They use a 0W-16/20 oil with ~280°F sump temp and ~355°F at bearing exit. (measured at Daytona summer race) The bearings are already running on the edge of metal fatigue from the heat. If they were to pour in a 50 grade oil, it's unlikely the engine would survive the race. The increase in hydrodynamic friction and slowing of oil flow would cook the bearings.

 

[Wiremanjon]

My new 2025 Toyota Camry is a 2.5 L hybrid and calls for 0W-8 GLV-1 oil. My wife takes it for many short trips(5 miles each way to work and 2 miles each way to supermarket with occasional once monthly hour long trips). I already ordered Amsoil 0w-8 for the first 5,000 mile oil change. I will send a sample to Blackstone labs. Other than doing the 5,000 mile changes instead of 10,000 mile changes, what’s an owner to do? I plan to keep the car for ten years-indeed I already purchased a 10 year/100,000 mile warranty.

 

[Mechanician]

Amsoil, Mobil One, and Valvoline are all blending hybrid oils now.
May be just marketing, all claim better protection from moisture contamination.

https://www.amsoil.com/p/amsoil-0w-8-100-synthetic-hybrid-motor-oil-he08/

 

[Kalle.J]

My new 2025 Toyota Camry is a 2.5 L hybrid and calls for 0W-8 GLV-1 oil. My wife takes it for many short trips(5 miles each way to work and 2 miles each way to supermarket with occasional once monthly hour long trips). I already ordered Amsoil 0w-8 for the first 5,000 mile oil change. I will send a sample to Blackstone labs. Other than doing the 5,000 mile changes instead of 10,000 mile changes, what’s an owner to do? I plan to keep the car for ten years-indeed I already purchased a 10 year/100,000 mile warranty.

Wait six months, it will very likely be back specified to JASO GLV-2 (0W16 & 0W20).

https://www.lubesngreases.com/luber...globe-commissions-engineering-for-rerefinery/
https://saemobilus.sae.org/papers/d...osity-index-gasoline-engine-oils-2025-01-8468

 

[TiGeo]

Getting ready to head to VIR this weekend for a 2-day HPDE. A buddy tracks his GR Supra and I just found out he runs the factory recommended 0W20 and will be there...he has several track days on it so far....my prediction? Will be fine...

 

[kschachn]

Getting ready to head to VIR this weekend for a 2-day HPDE. A buddy tracks his GR Supra and I just found out he runs the factory recommended 0W20 and will be there...he has several track days on it so far....my prediction? Will be fine...

Why would he do that? To what advantage?

 

[TiGeo]

And also just found out another buddy with the same GR Supra tacking it....run Motul XCess 5W40. A true thin/thick Supra battle!

 

[Wiremanjon]

Wait six months, it will very likely be back specified to JASO GLV-2 (0W16 & 0W20).

https://www.lubesngreases.com/luber...globe-commissions-engineering-for-rerefinery/
https://saemobilus.sae.org/papers/d...osity-index-gasoline-engine-oils-2025-01-8468

Good to know they’re working on it!

 

[TiGeo]

Why would he do that? To what advantage?

B/c "The manual says this is what it takes" I'm sure. I'll talk to them this weekend.