Oil Weights

[ezbmr]

When some 5w30s are more like 5w40s or 10w40s and some 0w30s are like 5w30s, why do we concentrate on the weight? Perhaps that is for the sheep that don't care?

[BoldUlysses]

What?

[Eta power]

Oil weight is one of the two important factors when choosing oil for your car. The additive package is the other....

[sprintman]

OP is one of the very few with a handle on oil. A 30W say can vary in viscosity from nearly a 20W at the low end to nearly a 40W at the high end so picking an oil that meets spec via SAE viscosity is almost irrelevant. Spec is LL01,but ACEA A3,B3 as a minimum. So a viscosity around 12.0 cSt @ 100C, and more importantly a minmum HTHS of 3.5. XW40 for most countries except for the U.S which has CAFE so BMW 5W30 LL01 was created. I want some margin for viscosity loss when the oil shears, and all oil shears, so no BMW 5W30 for me. XW40 meeting LL01 in my BMW.

[robmpulse]

OP is one of the very few with a handle on oil. A 30W say can vary in viscosity from nearly a 20W at the low end to nearly a 40W at the high end so picking an oil that meets spec via SAE viscosity is almost irrelevant. Spec is LL01,but ACEA A3,B3 as a minimum. So a viscosity around 12.0 cSt @ 100C, and more importantly a minmum HTHS of 3.5. XW40 for most countries except for the U.S which has CAFE so BMW 5W30 LL01 was created. I want some margin for viscosity loss when the oil shears, and all oil shears, so no BMW 5W30 for me. XW40 meeting LL01 in my BMW.

What makes you think the proper 5W-30 is not available in the US?

Sorry, I read your post again...... let me change my question...

what makes you think the proper 5W-30 is not good for your car?

[sprintman]

Too close to minimum spec when new, and when it shears during use most will be below spec. As I said I want some margin and so do most BMW owners worldwide hence they and the dealerships use XW40, not 5W30. Cost is the same so not an issue. Make sense?

[325bob]

Too close to minimum spec when new, and when it shears during use most will be below spec. As I said I want some margin and so do most BMW owners worldwide hence they and the dealerships use XW40, not 5W30. Cost is the same so not an issue. Make sense?

"make sense"? ,not really, what viscosity is"X" oil,as if the pletora of "multi-weights"(oxymoron) wasn't confusing enough, they come up with XW40!

[GunnerNell]

No, sprintman writes "X" (in XW40) as a variable to indicate that it's the operating temperature weight of the oil he's talking about. Could be 10W40, 5W40, perhaps even 0W40. I'm pretty sure sprintman means that these cars work better/longer with an oil that acts like a heavier weight (40) at operating temperature. (Having read many of his posts, I'm sure sprintman will chime in and correct this if I'm wrong. I'm jumping in here because it's Australia time where he is, and I don't know when he might be available to answer your question.)

But now that we're talking about it, the "W" in multi-weight oils refers to the cold temperature weight; actually, I believe it stands for 'winter,' a holdover from when this stuff was first developed. Obviously, that cold temp weight is important only for concerns relating to start-up and the first few minutes of operation, until full operating temperature is reached.

But that's not an unimportant number either. Around 20 years ago, one of Quaker State's additives for cold weather temperature weights was defective, and QS ended up paying for quite a few new engines -- I know of at least several Mercedes Benz engines -- that were damaged because they weren't getting full oil circulation in cold weather. [Actually, there was litigation, and I believe QS ended up collecting from the additive manufacturer.]

Anyway, as I understand it, the weights are not exactly 5W or 10W, for example. It's just that they act like 5 or 10 weight oil in the cold. Sprintman?

[Wildman518]

No, sprintman writes "X" (in XW40) as a variable to indicate that it's the operating temperature weight of the oil he's talking about. Could be 10W40, 5W40, perhaps even 0W40. I'm pretty sure sprintman means that these cars work better/longer with an oil that acts like a heavier weight (40) at operating temperature. (Having read many of his posts, I'm sure sprintman will chime in and correct this if I'm wrong. I'm jumping in here because it's Australia time where he is, and I don't know when he might be available to answer your question.)

But now that we're talking about it, the "W" in multi-weight oils refers to the cold temperature weight; actually, I believe it stands for 'winter,' a holdover from when this stuff was first developed. Obviously, that cold temp weight is important only for concerns relating to start-up and the first few minutes of operation, until full operating temperature is reached.

But that's not an unimportant number either. Around 20 years ago, one of Quaker State's additives for cold weather temperature weights was defective, and QS ended up paying for quite a few new engines -- I know of at least several Mercedes Benz engines -- that were damaged because they weren't getting full oil circulation in cold weather. [Actually, there was litigation, and I believe QS ended up collecting from the additive manufacturer.]

Anyway, as I understand it, the weights are not exactly 5W or 10W, for example. It's just that they act like 5 or 10 weight oil in the cold. Sprintman?
I thought this was the universal understanding about oil??? That's what I was told, and my BMW dealer uses 5w-30 for the record.

[325bob]

No, sprintman writes "X" (in XW40) as a variable to indicate that it's the operating temperature weight of the oil he's talking about. Could be 10W40, 5W40, perhaps even 0W40. I'm pretty sure sprintman means that these cars work better/longer with an oil that acts like a heavier weight (40) at operating temperature. (Having read many of his posts, I'm sure sprintman will chime in and correct this if I'm wrong. I'm jumping in here because it's Australia time where he is, and I don't know when he might be available to answer your question.)

But now that we're talking about it, the "W" in multi-weight oils refers to the cold temperature weight; actually, I believe it stands for 'winter,' a holdover from when this stuff was first developed. Obviously, that cold temp weight is important only for concerns relating to start-up and the first few minutes of operation, until full operating temperature is reached.

But that's not an unimportant number either. Around 20 years ago, one of Quaker State's additives for cold weather temperature weights was defective, and QS ended up paying for quite a few new engines -- I know of at least several Mercedes Benz engines -- that were damaged because they weren't getting full oil circulation in cold weather. [Actually, there was litigation, and I believe QS ended up collecting from the additive manufacturer.]

Anyway, as I understand it, the weights are not exactly 5W or 10W, for example. It's just that they act like 5 or 10 weight oil in the cold. Sprintman?

Thanx, Gunner, I was just venting, after 30 years of this "multi-weight" BS, I get testy. , I remember the 5weight sewing machine oil, and don't think I'd trust it in a FI Bimmer motor at 7K clawing at hot asphalt with some 3.15 Kumhos. Remember, the super thin oils were all CAFE driven, I'm pretty sure that thin oil shears easier than thicker oil, unless the additives can alleviate that, but then, why would BMW call for higher viscosity in the higher stressed engines?

[GunnerNell]

I certainly didn't think I was saying anything of a groundbreaking nature, just trying to respond to what I thought was a question about sprintman's post. And since I used to get paid by the word, I ran on a bit... . Sorry.

[sprintman]

GN is correct X = 0/5/10 whatever. Just remember BMW 5W30 meets spec, most XW30's dont. Even easier look for 'meets LL01' and you can't go wrong. But you know somebody will still post 'I use Mobil 1 5W30 is that OK?'