Why do people still use 10w-30 in summer and 5w-30

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The_Eric

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In the winter, when a decent 5w-30 should replace the 10w-30 for year round use? In some cases, I can see someone (an informed person) picking 10w-30 if it had a few ticks more viscosity or a touch higher HT/HS over a 5w-30 in their favorite brand, but for the majority of people, a 5w-30 should due just fine. I suppose there also are a few applications that would favor a 10w for the sake of shear stability too.

It would seem that today's technology and resources have made a 5w just as durable as a 10w, so I would think that people would benefit from the increased flow and pump-ability and teeny increase in fuel economy when the oil isn't at operating temp.

Am I off base? I ask not only for my own sake, but to also levy a more convincing argument on the benefits of 5w in place of 10w when discussing with the boss or customers.
 
I am pretty sure that most of the 5 and 10w30 of the same brand actually have different hot flow properties. Maybe not by much, but a little bit.

I am one of those people who switch. For one thing, my cars consume oil. Secondly, when I am buying, there is usually more 10w30 available of the oil I am buying (On sale) so buying 5 and 10w30 is usually easy and I sleep well at night.

Although I generally agree, a 5w30 year round WOULD be fine.
 
Familiarity breeds a sense of comfort and people tend to follow what they seen growing up. For some reason, people tend to never read and heed what an owners manual recommends for weight and type of oil.

As each decade comes around, people seem to be a decade behind the times in what they put in their vehicle.

What I think make now and the future decades to come different, is that there will not be a "one size fits all" weight for vehicles and it will get even more confusing as to why people do what they do.
 
I'm one of those people. I use 10W-30 in the summer because it has less VI than 5W-30. Less VI means fewer engine deposits - hence the trade-off. Plus, the 5W buys you only approximately 15°F over 10W for the same startup viscosity, so it's not that big a deal to move up a grade in the summer.
 
In the main menu of BITOG, there is lots of info on oil 101 and more definitions for the webster crowd, but good stuff. A fun read in MO>
 
Until I came on here, that's exactly what I did because it's what the manufacturer recommended - and I'm sure many car owners do the same. I shied away from "lighter" weight oils because I thought they weren't thick enough. When first reading BITOG and seeing people using 0w20 instead of 10w30, I cringed.

While there's nothing wrong with following the manufacturer's recommendations (especially under warranty), the same logic that causes someone to use 5w30 in the winter can be extended to using a 0w30 year round.

So now that I'm better edumacated
thankyou2.gif
0w30 is the flavor.
 
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Why do people still insist that they need straight 30 in the winter and straight 40 in the summer, "...'cause that 5W30 is too thin fer' the way I use muh truck..."?

Why did I use 5W30 in my 5W20 spec'd car? Because I had it. I bought several cases of Trop-Arctic 5W30 semi-syn when it was $1.79 a qt before I bought my Mazda. I miss that stuff (at that price...I'm not that attached to any one brand) The 5W30 worked well enough that I never bothered to use 5W20....maybe next change.
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So I suppose the answer to your question would be, Because they can
 
Multigrade dinos have a lot of vii and the drawbacks associated with this additive. They are getting better, but methacrylates are NOT oil and can gum and varnish up the works. SAE 30 is a stable oil and things go south from there. Look at all the UOA with the common 5w-XX oil shear out of grade - MY engines dont tolerate under grade viscosity the way I drive. I Find it odd that the general pop here doesnt understand the performance compromises required to make a multivis oil. a 10w-30 is prob the least compromised oil. Most 5w-xx are at the upper limit for volatility. When I find a good 5w-30 SM/SL I'll let you know - I havent yet. Thats why my next car needs to be a ford modular - I can run the C-P 5w-20 and "foggiddabout it!"
 
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It makes more sense because in Winter its a little bit better to have a "5" and in Summer 10W-30 burns off less. Especially in Dino.

You could run a 10W-30 year round though.

This is for cars where a "30" is thick enough.

Some people run 10W-40 year round too and thats fine right to around ZERO degrees then its too thick. Maybe FOUR degrees..
 
I can honestly say I have never swapped between 5W and 10W based on warm/cold times of year. I have run 5W-30 -OR- 10W-30 year round in any vehicle calling for 30 weight. I would swap between heavier and lighter weights back when I had hi-perf vehicles. 10W-40 or 20W-50 in the warmer months and 10W-30 in colder.
 
Changing oil wts from summer to winter is old school. No needfor that now adays. In the 60s I used Valvoline straight 20 Wt in the winter and 30 wt in the summer. That was in Maine.
 
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Originally Posted By: webfors
What Kestas and ARCO said.

It's only old school for tig because he's a syn lover
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I thought I nailed it too...

I can tell you that on 110-degree days, a LOT of 5W-30 cars "Burn off a quart." Checking the Oil level every week will reveal. Now, when standing there melting and the AC is on (Engine load) and you need to select an Oil. Which do you choose? The 5W-30, which BURNED OFF? Or the 10W-30, which SHOULD RESIST THAT MORE?

Ill go with 10W-3o for $400, Alex.

Now, in the winter when your feet are frozen to your shoes and also the ground and it is a COLD ZERO and you also have this same choice. You check your Oil level in your bundled-up coat, and you pop the hood, after un-freezing it and cursing at how cold it is. You go to add Oil, you go into the store. On your left, is the 5W-30. On your right, is the 10W-30! Which do you choose!?

???

"I will select 5W-30 for $600, Alex."

"Answer there is the DAILY DOUBLE!!"

lol.gif
 
Is there any way to tell how much VII an oil has? Other than looking at the weight and saying all 5W30 dino has more VII than a 10W30 dino because of oil blending tradeoffs.

And where does a 5W20 dino fit in as far as VII? More, less, or in between a 5W30 and 10W30 dino?
 
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Unless you were at an extreme would it really matter? Then we could say since a syn 10w could possibly flow as well as a dino 5w the 10w syn should be a better choice? Just wondering.
 
Let's say that you found a bunch of PP on clearance for $1.49/qt.
Let's say that some was 5W-30, but most was 10W-30.
Would you foresake this fine oil at a killer price just because you don't think you should use 10W-30 in a place with real winter?
Of course not.
You'd buy all that the store(s) had, and you'd use the 10W-30 spring/summer/fall, and the 5W-30 winter.
If you could have bought all 5W-30 at the killer price, you would have.
I have some 10W-30 and even 15W-50 syn oil bought at a price I couldn't pass up.
An oil that is fine for the warmer months might not suit the colder ones, but that doesn't mean you can't use it, or that you have some aversion to running 5W-30 over the summer.
 
Exactly.
If you have a bunch of different grades in the stash, you use them as appropriate.
Thicker summer, thinner winter.
Why not?
 
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