"Cushion" of a more viscous motor oil worth it?

[wemay]

We've all seen the posts where a member offers genuine advise to the tune of, "i would recommend a heavier viscosity so you have more of a cushion...." As opposed to running what the manufacturer recommends.

How much is a cushion worth? Does it really afford you the ability to transform a vehicle with a machining issue, dilution, design flaws, into a reliable non-oil consuming ride for an appreciably longer period?

Assuming it's under warranty, would you even want to mask what you consider an issue since it may only "prolong the inevitable" (if a design flaw) until after your warranty is over, if that long?

EDIT: not talking about cars you take to the track. Just daily drivers.

 

[KGMtech]

The engine in most BITOG cars, daily drivers, will far outlast the chassis of the car - regardless of what weight of oil is used. 300k miles is routine if owners manual is read and followed, so how long do you want your engine to last? what if the body rots, or the interior degrades or you want the newest features?

 

[dogememe]

5w30 vs 5w20 in Fords is good

both of mine are happy!

 

[RDY4WAR]

Depends on what viscosity you're talking about, and what you consider a cushion. I like the lowest kinematic viscosity @ 100*C paired with the highest HTHS @ 150*C possible for that viscosity. Ultimately the HTHS determines your cushion and some 30 grades have a higher HTHS than some 40 grades, some 20 grades higher than some 30 grades, etc...

I like to think of a higher dose of ZDDP as a contributor to that cushion as well.

 

[StevieC]

As I said in the other threads on the subject I think a normal daily driver vehicle operated under normal conditions where a 20wt is recommended will be more than fine and a thicker weight isn't necessary. Many engines live very long lives on these thinner weights. I think what is more important is a quality lubricant with a good filter changed at a reasonable OCI based on the application etc.

This doesn't go for towing/hauling/extreme heat/beating on a Turbo or racing.

 

[buster]

It really depends as there is no one answer to this question. My thoughts are to stick with the grade that is called for, as long as undw warranty or go just one grade up. You'll find most 30 grades are around 3.0 for HT/HS. Someone recently recommended Mobil 1 0w40 in a new 2017 Civic. He appears to work for an oil company too.

As the car ages moving up a grade or so is not a bad idea. Especially in engines that have fuel dilution issues.

I currently have 54k on my car and for my next change I think I am going with a 5w30.

Engines are outlasting the rest of the car these days, so it appears. Once a car starts to nickel and dime you, I'm done with it. Ain't nobody got time fo dat!

 

[PimTac]

More and more engines are being designed and manufactured with 20wt oil in mind. I know my Mazda SkyActiv engine is like this. Changes in designs plus better alloys and other materials used all add to the total picture

 

[gathermewool]

Great thoughts, so far. My answer to these kinds of questions is usually: it depends. Saying the context is strictly limited to DD vehicles with some unknown issue is still way to general.

Specifically, I would say that most design flaws and manufacturing defects cannot be fixed by any one oil. E.g., if an engine's piston, ring pack, cylinder, PCV system, etc design causes excessive consumption, or if there's an improper bearing clearance that makes for a much higher probability of spinning a bearing, then changing the oil will not appreciably affect failure rate over the life of the vehicle.

That's not to say that oil selection is meaningless in vehicles that have issues, but not ones that will ever cause direct catastrophic failure. Sometimes, a bandaid can let the engine still outlast the rest of the chassis.

In other cases, such as if poor lubrication beneath the crown and cylinder wall to ring area results in stuck rings, or for things like flat tappet cam designs (just as an example; understand that this design is not common at all now a days),then a more robust oil will likely be more beneficial than one with just a higher viscosity.

 

[tig1]

Originally Posted by dogememe
5w30 vs 5w20 in Fords is good

both of mine are happy!



0-20 is very happy in my Fords!!

 

[slacktide_bitog]

On a turbo, especially a TGDI, it is definitely worth it

Remember that masking an issue or using a band-aid was why BMW used Lucas Stop Leak 10w60 on some of their M-cars. Also, HM oils are usually slightly thicker than their non-HM counterparts.

 

[zorobabel]

Originally Posted by KGMtech
The engine in most BITOG cars, daily drivers, will far outlast the chassis of the car - regardless of what weight of oil is used. 300k miles is routine if owners manual is read and followed, so how long do you want your engine to last? what if the body rots, or the interior degrades or you want the newest features?

Around here not passing smog is my main concern.

 

[VeryNoisyPoet]

Here's an example of a non-track use that's fairly hard on a daily driver. My car's oil will run 90C to 105C (194F to 221F) during a normal highway cruise, with oil pressure around 45 psi at 2400 rpm. If I'm on a mountain grade at freeway speeds in 3rd gear at 3600 rpm for an extended amount of time with a heavy load on board, oil temps can rise to 127C / 260F. Pressure will drop to 35 psi despite the higher rpm due to decreased viscosity. This is with an oil to coolant heat exchanger.

A thin oil will provide plenty of protection at standard temperatures, but may thin out too much when pushed hard, even if not being thrashed on the track. Won't cause rapid failure, but may accelerate wear if the vehicle is routinely operated under heavier load in hot ambient temperatures.

The other concern with DI and turbocharged engines is fuel dilution thinning the oil further even if temperatures remain sane. A higher initial viscosity oil can tolerate more contamination before its lubrication properties are compromised. In a highly stressed turbocharged engine, thin contaminated oil is the last thing you want when boost comes up.

 

[dogememe]

Originally Posted by zorobabel
Originally Posted by KGMtech
The engine in most BITOG cars, daily drivers, will far outlast the chassis of the car - regardless of what weight of oil is used. 300k miles is routine if owners manual is read and followed, so how long do you want your engine to last? what if the body rots, or the interior degrades or you want the newest features?

Around here not passing smog is my main concern.

It's amazing how many quality, drivable vehicles are sent to junkyards due to not passing smog because the cat is a little worn out or it uses a little oil. I'm sure the environmental effect of many new vehicles purchased by the time you count the manufacturing and shipping is worse than keeping the same older car on the road another few years til the tranny blows up or something. I think they need to move the smog exempt age from 1975 to 20 years... like 1998 or something.

 

[wemay]

Originally Posted by slacktide_bitog
On a turbo, especially a TGDI, it is definitely worth it

Remember that masking an issue or using a band-aid was why BMW used Lucas Stop Leak 10w60 on some of their M-cars. Also, HM oils are usually slightly thicker than their non-HM counterparts.


This combo (DI + Turbo + 0w20) is probably the one that has the most "go up a grade or two" recommendations, i.e., Honda's 1.5T-GDi Earth Dreams and Ford's 1.0T and 1.5T EB applications for example, 5w20 and 0w20 respectively. But many normally aspirated applications as well.

 

[BrocLuno]

Originally Posted by KGMtech
The engine in most BITOG cars, daily drivers, will far outlast the chassis of the car - regardless of what weight of oil is used. 300k miles is routine if owners manual is read and followed, so how long do you want your engine to last? what if the body rots, or the interior degrades or you want the newest features?


That works back east, but not out here. The chassis will outlast the engine by many times over. So the OP's question is really a regional thing.

I'll take reduced bearing and ring wear any day over saving 10 gallons of gas a year (if that). To do that, the system must be in hydrodynamic lubrication 99.99% of the time.

And, it's an engine wear issue as far as which "thicker" oil is better. By the time you need 20W-50 for most modern engines, they have been long due for an overhaul. OTOH, for engines from the 1970's and/or the UK maybe up to the 1980's - that's not an overly thick oil.

I usually run a 30 something up to what I consider mid-life (say around 125,000 miles), then bump up to a 40 something as in 15W-40 out to 250,000 miles + ... I have never owned anything that spec'd a 20 when new ... And if I did, I'd be looking at the world wide owners manual recommendations for that model engine.

CAFE can easily work for the rust belt folks because their chassis will be gone long before the engine. So there is a place for that strategy - just not in my back yard

 

[Rolla07]

I have yet to see any evidence that proves anyones opinion for using thicker oil than what the mfr suggests.

 

[BrocLuno]

You have not been reading the technical papers section often enough ...

I'll look for the ring wear charts later this evening ...

 

[SavagePatch]

Originally Posted by slacktide_bitog
Also, HM oils are USUALLY slightly thicker than their non-HM counterparts.


You said "usually" so you probably already knew this but I wanted to point out to everyone else that PPHM is thinner than PP and PUP.

 

[StevieC]

Chromium would be indicative of ring wear right? If so mine was 0ppm on my UOA in the Journey with 9K on the 5w20 oil. I should have more than 0ppm if the rings were wearing. I should also have aluminum for the piston and that was also 0 and the iron was 4ppm which is really low for normal wear. This was an engine that was spec'ed for a 30 weight previously as well.

I'm not saying all situations are like this but in this case it was and many engines seem to go a long life with 20 weights. We have had them for over a decade now and now they are moving some engines to 16 weights. I couldn't see OE's doing this if they weren't sure that this oil would give long engine life.

 

[RDY4WAR]

Let's say you have two oils.

5w-30
Visc. @ 40°C: 62.5 cSt
Visc. @ 100°C: 10.5 cSt
HTHS @ 150°C: 3.0 cP

5w-20
Visc. @ 40°C: 49.0 cSt
Visc. @ 100°C: 8.5 cSt
HTHS @ 150°C: 3.1 cP

We keeping talking about viscosity by oil grade but looking at these two above, which oil would actually be "thinner" in terms of more time spent in mixed and boundary lubrication in the rings and bearings?