Reason to NOT use 5w-30 over 10w-30?

[RegDunlop]

ANy reason I should not use 5w-30 in a car that has 10w-30 on the filler cap?

The manual recommends 10-30 until very cold temps, than allows for the use of 5-30.

But its' my understanding from what I have read that oil has gotten a LOT BETTER in the last 16 years.

The engine is a GM 3800 from 1995 with about 105,ooo miles on it.

 

[GMorg]

You can run 5W-30 or 0W-30 without worries.

 

[dparm]

No real reason. 0w30 and 5w30 are more commonplace now than they used to be.

 

[The motor guy]

The 5w30 has more viscosity index improvers vs the 10w30 so technically the 10w30 would have more oil that lubricates the engine. But no it won't hurt to use 5w30. The 5w30 when cold will still be thicker than the 10w30 when hot anyways so it doesn't matter.

 

[chubbs1]

I think 10w30 is the forgotten oil, it is still a viable option in warmer climates. That being said I have been using 0w30 5w30 and 10w30 with no problems.

 

[armos]

It's not critical, but generally 5w30 is thinner than 10w30, even when warm. But if you do a lot of short trips in the winter then 5w30 might be better. When fully heated up, I'd want 10w30 in it though.

A relative's 1997 3800 has wiped 2 rod bearings, once on cyl5 and more recently on cyl6 (despite oil pump being replaced). Those bearings are at the losing end of the crank. I don't know why it happened, obviously that's not normal and it's just a personal anecdote, but if that's a common failure point then I'd avoid going any thinner in that engine.

GM usually recommended 5w30 on most engines since the 80s, so they may have been worried about something if they recommended 10w30 on the 3800. But still, it's not a huge difference between them and 5w30 is better when cold.

 

[gulian]

excellent reply Armos, I also agree with you about GM recommending 10w30 for a reason.

 

[qdeezie]

I use 5w-30 in 10w-30 applications regularly with no ill effects.........however if I find a smokin' deal on 10w-30, I use the 10w-30 as a summer oil.

 

[OldCowboy]

Originally Posted By: armos
It's not critical, but generally 5w30 is thinner than 10w30, even when warm. But if you do a lot of short trips in the winter then 5w30 might be better. When fully heated up, I'd want 10w30 in it though.


While this may have been true 20 years ago, it is no longer true, at least with synthetics. Here are the values for 4 commonly used synthetic oils:

Code:


Mobil 1 5W-30 10W30

Viscosity @ 100C 11 10.1

Viscosity @ 40C 61.7 63.2

Viscosity Index 172 146



Amsoil Signature 5W-30 10W-30

Viscosity @ 100C 10.5 10.5

Viscosity @ 40C 60.3 62.9

Viscosity Index 166 157



Mobil 1 EP 5W-30 10W-30

Viscosity @ 100C 10.6 10.2

Viscosity @ 40C 59.8 63.7

Viscosity Index 169 147



Pennzoil Ultra 5W-30 10W-30

Viscosity @ 100C 10.3 10.3

Viscosity @ 40C 57.5 61.9

Viscosity Index 169 156


In all cases, the 5W-30 is at least as viscous at operating temperature (100C/212F) as the 10W-30. In the cases of the Mobil 1 oils, the 5W-30 is actually "thicker" at operating temperature than the 10W-30.

 

[ltslimjim]

^...and if say, for instance, the Viscosity Index Improver(s) are of the better quality to cover that greater operating range; along with base stock quality etc, this will show over the course of an interval more than just 5w-30 compared to 10w-30 in a general sense or on paper; then again some paper says differently from the virgin state. Again, which product holds to the virgin numbers better than another product(multi-grade spec included) is the overall product quality in all of it's aspects.

That said, a good 10w-30 is still fine to run in the summer these days, but not necessary 'as opposed' any longer to higher quality 0/5-30 oils now available. Yet, this isn't a one size fits all, some vehicles simply have spec'd what turns out to be at the borderline thinnest 'recommended' oil at the 'standard' and in fact may perform better on another grade(note, see maxima owners using 40 multi-grade over 30)...still other domestic engines could prefer 10w-30 of 5w-30, if you are looking two conventional oils more so. My dad's truck seems to want a slightly thicker 'brew' and he prefers conventional or a blend.

 

[aquariuscsm]

Related to the topic,what`s the real world difference in protection from a 10W30 vs a 10W40? Pros and cons of each?

 

[Merkava_4]

Originally Posted By: RegDunlop

The engine is a GM 3800 from 1995 with about 105,000 miles on it.


I run MaxLife 10W-30 (per owners manual) in my 3800 and then I top off with 10W-40.

My way of thinking is that the 10W-40 counteracts the sheering down affect of the 10W-30.

 

[RegDunlop]

The thing is I ususually would just buy 10-30 but I was able to get some 5-30 M1 HM AND REGULAR M1 5-30 basically for $15 and I want to run a mix of 3 qts regular m1 5-30 and 2 qts m1 HM.

 

[T-Keith]

I've run 5w30 in all my 3800s for years. I've had 6 with over 100,000 miles, one with over 300,000. 5w30 is often better chemistry than 10w30 and rarely thinner than 10w30 at operating temp.

armos, if they wiped a bearing, I can guarantee it was coolant contamination. The series II engines have trouble with the intake gaskets when the coolant doesn't get changed. Every single one I've taken apart has had bad gaskets, and most people don't notice or care to fix them.

 

[armos]

Originally Posted By: OldCowboy

While this may have been true 20 years ago, it is no longer true, at least with synthetics. Here are the values for 4 commonly used synthetic oils:

Code:


Mobil 1 5W-30 10W30

Viscosity @ 100C 11 10.1

Viscosity @ 40C 61.7 63.2

Viscosity Index 172 146



Amsoil Signature 5W-30 10W-30

Viscosity @ 100C 10.5 10.5

Viscosity @ 40C 60.3 62.9

Viscosity Index 166 157



Mobil 1 EP 5W-30 10W-30

Viscosity @ 100C 10.6 10.2

Viscosity @ 40C 59.8 63.7

Viscosity Index 169 147



Pennzoil Ultra 5W-30 10W-30

Viscosity @ 100C 10.3 10.3

Viscosity @ 40C 57.5 61.9

Viscosity Index 169 156


In all cases, the 5W-30 is at least as viscous at operating temperature (100C/212F) as the 10W-30. In the cases of the Mobil 1 oils, the 5W-30 is actually "thicker" at operating temperature than the 10W-30.


Interesting. 10w30 noticeably raised warm oil pressure on my car (not a 3800), but that was with conventional and I'm only assuming that the oil I inherited from the previous owner was 5w30 (what's written on the cap). It also may have just been overdue and sheared down badly.
I wouldn't doubt that more aggressive multiweights work better with synthetic, otherwise they wouldn't have grades like 0w40 and 5w50 out there. By synthetic standards 5w30 is pretty mild.

 

[Stelth]

I recently got a 2001 GMC van with the 4.3L v-6, and I decided to use VWB 10w-30 over 5w-30 for the sole reason that the 10w-30 has a 22% lower NOACK than the 5w-30, 11.3 vs. 14.4. I've noticed that a lot of the SN conventionals in 5w-30 have fairly high NOACK numbers, with some going over 15. Also, I'm hoping that the 10w-30 will be a little more shear stable.

In the long run, in southern California, I doubt that any advantage of one over the other will amount to a hill of beans, but if I didn't want to overthink these things, I wouldn't be at BITOG.

 

[hominid7]

Originally Posted By: Stelth
but if I didn't want to overthink these things, I wouldn't be at BITOG.


Best quote of the day!

 

[A_Harman]

If you are talking about running synthetic 5w30 or 10w30, I would say there is no reason to to get the 10w30. Modern synthetic base stocks have high enough VI that they don't hardly need much VII to make the 5w- rating.

If you are talking about running conventional 5w30 or 10w30, I would say to get the 10w30. A conventional 5w30 would contain more VII's to get the 5w- rating than would a 10w30. I think the 10w30 would be more shear stable and less prone to sludging.

 

[Ram01]

you got it 10w30 will offer better wear protection and longer oci

 

[ltslimjim]

Originally Posted By: A_Harman
If you are talking about running synthetic 5w30 or 10w30, I would say there is no reason to to get the 10w30. Modern synthetic base stocks have high enough VI that they don't hardly need much VII to make the 5w- rating.

If you are talking about running conventional 5w30 or 10w30, I would say to get the 10w30. A conventional 5w30 would contain more VII's to get the 5w- rating than would a 10w30. I think the 10w30 would be more shear stable and less prone to sludging.


Great reasoning, here. I agree actually. Now, if only to convince my dad...5w-30 it is for the winter time, still, though!