5W30 recommended, 10W30 used, how many do this

[bchannell]

With all the talk of which is the better way to go, I wonder, in an engine spec'd (recommended) for 5W30, what are most of you running. Do you stick with it, or go 10W30 or something else. Most of the guys I know, simply always use 10W30 in the summer and 'maybe' go to 5W30 in winter. I haven't searched the UOA's yet, but does 10W30 shear less in the heat of summer than 5W30? Do cold starts in summer time with 10W30 cause any more noticable wear in your opinion?
Without any data to back it up, my gut feeling is, this is another issue that the difference between running 10W30 in place of 5W30, or probably 5W20, year round would be negligible.

 

[addyguy]

2002 Chev Cavalier 2.2 OHV, 5w-30 on cap.

Most of my oil changes have been with 5W-30, but I have done 2 changes with GTX 10W-30, and the engine on those OCI's used half the oil it did with 5W-30. I've also been topping off my 5W-30 w/10W-30 Havoline (old stuff), and again, the oil consumption slows when I do this. Not scientific, but engine also 'feels' smoother when usng 10W-30.

I'm planning on going even further to test this during the summer; either using 5W-40/10W-40 weight, or spiking my 30-weight with STP/MLEP, to see if I can reduce the piston slap and 'shake' this engine has. This engine is an 'old school' OHV GM design, so I think heavier oil is better suited to it....

 

[Bulli]

1996 cavalier: 5-30 winter 10-30 the rest of the year. Less oil consumption and quieter engine. Maybe some less MPg but yah.
I have been doing this for the life of the car and will continue to do it until this [censored], oil eating engine dies on me

 

[BGPKR]

04 Subaru STi, 5w30 recommended, I use either 10w40, or 5w40. The 5w30 seems to burn off too easily.

 

[XPR]

I'd use 5W-30 or 0W-30

 

[ikeepmychevytoo]

My engine sound quietest and feel happier with the thinner 5w 30s. Occasionally I buy 15w 40 or 10w 30 if I find something as cheap and has good specs and use in the summer. This is usually a HDEO in 7lt jug and has a SL or SJ to attract the fleet buyers. They are usable for my manual but it advises for the thinnest possible oil in the expected temperatures. 5w 30 defined as the thinnest. It goes...
Code:
to 38°C.... 5w-30

above -18°C....10w-30

above -12°C....15w-40

above -7°C....20w-20

above 4°C....30


It is confusing because looking at the viscosities, a straight 20w 20 or a 10w 30 looks thinner than the 0w 30 at 40°C/104°F ! A straight 30 looks thinner than the 10w 40.

Code:
kinematic viscosities at 40°C mm^2/s. (ASTM D445)



104.7...15w 40 Shell / Rimula

104.0...15w 40 Mobil / Delvac MX

95.0...10w 40 Shell / Rimula Super FE

86.2...SAE 30 Shell / X-100 (API SF)

80.0...10w 30 Petrol Ofisi / Optimus (local brand)

72.0... 0w 30 Castrol / Formula SLX LongTec

69.0...10w 30 Petrol Ofisi / Süper Dizel (local brand)

68.0...20w 20 Shell / Rimula

58.0... 5w 30 Total / Quartz

57.4... 5w 30 Shell / Helix F

56.1... 5w 30 Elf / Evolution SXR

43.5...10w Shell / Rimula

 

[BuickGN]

Mine calls for 5-20 and I use ACD 30/10-30 year round. It doesn't get that cold here in the winter and I have always paid close attention to how long it takes for the oil pressure light to go out. I've never noticed a difference all the way from 5-20 to straight 30. The car feels stronger and sounds healthier in the higher rpms. The only place I can tell a small difference is on cold starts for the first 5 minutes or so. It idles a little rougher. Not bad, and anyone who isn't familiar with the car would not notice it.

 

[Dominic]

Calls for 5W30... I run 5W30. No problems
What I search for is "the best oil in the grade"

If I lived in AZ, I might up to a 5W40.

 

[kokopelli]

manual and oil cap say 5w-30. have been using 10w30 year round, without any issues. winters here do get cold (in the 20s), but not below 0.

have also used various filters, again, with no noticeable issues.

 

[INDYMAC]

It's funny you ask this question. The last couple of times I checked in Wal-Mart to look at off the shelf oils for new offerings, the 10W30 spaces were all empty, and the other viscosities were all full. Now, that either means 10W30 has been discontinued, or that's all they use here in Texas.

 

[TallPaul]

My '92 Aerostar and '95 F150 both say 5w30 preferred, but allow for 10w30. I use 10w30 year round. Even if it didn't say 10w30 is allowed, I would still use it.

 

[mechtech2]

I can't see why anyone would like less flow when cold, with the thicker 10-30 [vs. the 5-30].
When hot, they are virtually the same.

 

[Dyoel182]

What if you prefer a little added protection instead of a little better flow? 10w oils will flow pretty far into below freezing temps anyhow.

 

[JAG]

Originally Posted By: mechtech2
I can't see why anyone would like less flow when cold, with the thicker 10-30 [vs. the 5-30].
When hot, they are virtually the same.

One has to know how oils are formulated and what effects certain formulation differences have on engine lubrication.

 

[Mystic]

In the case of my car 5W30 is recommended and 0W30 can be used in cold weather and 10W30 can be used only in warm weather. I try to use 5W30 most of the time but I have used 0W30 in the winter months. My car is a Saturn Ion and I checked with Saturn and apparently 5W20 can now be used. But it does not say that in my owner's manual so I will stick with 5W30.

I think as a car or truck ages and more and more miles are put on it probably would not hurt using a somewhat thicker oil in the warmer months only. I am going to start using 10W30 in the summer months only. But I would never use 10W40, 15W40, or 20W50 in my car.

 

[Dyoel182]

Originally Posted By: Mystic
I am going to start using 10W30 in the summer months only. But I would never use 10W40, 15W40, or 20W50 in my car.


Because of your climate and the glovebox manual recommendation or because you simply think they are too thick?

 

[Mystic]

It says in the manual that thicker oils like 10W40, 15W40, and 20W50 can't be used. In even says that straight 30 weight oil can't be used. The first Saturn I ever bought straight 30 weight oil could be used in summer months.

Personally I really don't believe in real thick oils anyway. Even in race cars (depending on what type of race car you are talking about) they have gone to lighter oils.

Diesel engines are a different story. Usually a diesel uses somewhat heavier oil, like 15W40 and 5W40.

In a newer car or light pickup truck or van or SUV I don't think I would go heavier than 10W30. And a lot of newer vehicles today are supposed to use 5W30 or 5W20. I would not want to go against what is said in the owner's manual. If you had a light pickup truck and you were going to do some towing or carrying heavy loads and if only 5W20, 5W30, or maybe 10W30 oil was allowed I think I would definitely go synthetic.

 

[Gary in Sandy Eggo]

Originally Posted By: bchannell
does 10W30 shear less in the heat of summer than 5W30? Do cold starts in summer time with 10W30 cause any more noticable wear in your opinion?

Yes, within any brand, 10W-30 will shear less than 5W-30 because there's less VI improvers in 10W-30 to shear.

Regarding noticeable wear on cold summer starts, I doubt you'll see any difference between the two. Where you'll see the difference is more wear at operating temperatures after the 5W-30 has sheared beyond what the 10W-30 could shear to.

Once the engine's at operating temperature (which can vary with ambient temperature), the thicker the oil (up to SAE-50 equivalent) the less the wear. Regardless of all the thin oil hype and voodoo, this remains unchanged. BIG HOWEVER . . . if you're easy on an engine, lower operating viscosities CAN provide the same protection as would a higher viscosity. What matters is how well the oil keeps the moving parts separated.

My car is spec'd for 5W-20, but the book goes on to say that 10W-30 is OK above 0F. My car will never see 0F or even 32F. Coldest it will ever see is 45F and this might be one or two nights per year. Most of the time cold starts will be as low as 50F in the winter, and 65F in the summer. Ambient operating temperatures will be 55-75F winter, and 65-85F summer.

I run 10W-30 in the winter, and SAE-30 monograde in the summer simply to get away from the VII of the 10W-30 oil. With the 10W-30 in the winter, the car consumes 1-qt between 5000-mile oil changes. With the SAE-30 in the summer, the car consumes about 1/4-quart between 5000-mile oil changes. So, even at a higher ambient temperature, the oil consumption is less with the mono-grade. There has to be a reason for that.

What I DON'T do with either oil grade is rev the engine with cold oil. I keep my rpm's under 1500 for the first few minutes, then gradually let it build to 2000 for 65-mph cruising speed if that's what's required.

Regards, Gary in Sandy Eggo

 

[wgtoys]

The old rule of thumb about a given brand 10W-30 shearing less than that brand's 5W-30 may well not be true anymore. It is quite possible that a given line of oil will use a better quality base stocks in it's 5W-30 than in the 10W-30, in which case all bets are off.

 

[Merkava_4]

Originally Posted By: Mystic
My car is a Saturn Ion and I checked with Saturn and apparently 5W20 can now be used. But it does not say that in my owner's manual so I will stick with 5W30.


I find that notion frequently on this board; a lot of guys are scared to death to deviate from the owner's manual.