Why do manufactures recommend/require the "w" and not leave it as optional?

[ZeeOSix]

It might be.
However, from what I've seen here at -4°F - 0W flows from the bottle the same way as, let's say, at 32°F.
And 5W looks is thicker at that temp.

All oil gets thicker as it gets colder, so even though the 0W "looks" to be flowing the same way at 32F as it does at -4F, it's really not. Hard to go by looks ... that's why there are viscosity measuring instruments. And of course a 5W should be thicker than a 0W at the same temperature, otherwise they wouldn't have a different W grade rating.

So, what you are saying is that an oil gets certain viscosity at certain temp. and there is no gradual thickening or thinning with dropping or raising temp.? Hence, oil viscosity and ambient temp. are not proportional?

Typical viscosity vs temperature curves. The colder it is, the more non-linear it is.

 

[Skippy722]

This is going to blow your mind: your washing machine has a setting for load size.

Yep, I was right, single dudes on a motor oil forum.

I tend to use bleach in my loads of white t-shirts and the wife's whites.

Married with 4 kids, we don't sort anything.... Granted none of us wear anything white either because that's a recipe for a very quickly stained shirt in our house. Not even our socks are white.

If the manufacturers put "use any 30 weight oil" on the cap/manual someone is going to dump some non detergent SAE30 in there and wonder why it's broken in 50k miles. Put "xW-30" on it and a ton of people will be wildly confused when they can't find exactly that on the shelf.

 

[Hohn]

Because CAFE requirements and the wide range of temperature variations in the North America I imagine. CAFE doesn’t really let manufacturers let us choose. But that’s just my guess.

100% correct. This is why they went from 5w-20 to 0w-20-- the EPA test cycle doesn't let the oil fully warm up so the lower viscosity of the 0w when cold gives them a tiny bit better performance on the gov't test cycles.

Gov't cycles start withe engine soaked at 20C-30C ambient temps for most of the cycles. One cycle involves colder temps (20F).

So for most of the test cycles, the engine will have lower pumping loss from a 0w vs a 5w and definitely vs a 10w.

 

[Ptm121]

Same here.

Me too!

 

[Leo99]

LOL. I have been happily married for 27 years and have two grown children.

There is no need to sort modern textiles unless your going to use traditional bleach. I wear almost nothing but white synthetic wicking t-shirts that don't hold stains and a little spray and wash fixes those, no bleach needed. My other colors don't run. Modern dyes don't run like they did 20 years ago.

Your living in the past or buying crap clothing.

We don't sort clothes unless there is a very specific reason. Like we bought something colorful in cotton of questionable quality. Like a homemade tie dye shirt off a hippie. And I'm not ashamed to admit, we wash permanent press clothes on the normal cycle.

 

[BMWTurboDzl]

Always lots of questions about the specifications by manufacturers.

Why do they see the need to stress one "w" over another? 0w or 5w for example

Could/should they just use "x" and leave it up to the users to decide based on location? Xw-16?

So many folks get hung up on the manufacturers recommendation and worry about warranty...which I understand.

Conceptual question about "why" stress a certain "w"...not about the virtues of the "w"

Emissions. Compared to a 5w-x in the same grade the 0w-x oils generate the least resistance during cold starts and during the warm up phase.

 

[Zee09]

I haven't seen yet any conventional or synth. blend 0W-20. Why is that?

You haven't looked hard enough..
I have pictures on here

 

[OM617YOTA]

100% correct. This is why they went from 5w-20 to 0w-20-- the EPA test cycle doesn't let the oil fully warm up so the lower viscosity of the 0w when cold gives them a tiny bit better performance on the gov't test cycles.

Gov't cycles start withe engine soaked at 20C-30C ambient temps for most of the cycles. One cycle involves colder temps (20F).

So for most of the test cycles, the engine will have lower pumping loss from a 0w vs a 5w and definitely vs a 10w.

Holy cats man, I knew the EPA testing would just be a representative test and wouldn't replicate what most people experience, but I had no idea it was this bad. What a garbage test, no wonder thinner oils do better.

Why would the EPA use a test that never gets the oil fully warm? Is that actually representative of how people use their cars?

Can't base it on my own experience, I live rural and going anywhere at all is a 20 min drive.

 

[Zee09]

 

[ammolab]

This is going to blow your mind: your washing machine has a setting for load size.

Yep, I was right, single dudes on a motor oil forum.

I tend to use bleach in my loads of white t-shirts and the wife's whites.

It actually automatically adjusts for load size. I’m up to date in the tech world….but I’m also an old rural, retired Boomer. So my only “whites” are those white socks everyone thinks we wear. Gosh, it would take 50 of them to make a small load. So the “mixed load” setting on the washer it is.