5w30 or 10w30 Which is better?

[BRUTE FORCE]

Manual says to use 10w30. Is the engine better protected with this grade of oil?

[2kg4u]

The first number is a measure of the oil's viscosity when the engine is cold, the second when hot. In my opinion 5W30 is too light for summer, but okay for the winter. If you want to run the same oil year round I would stick to the 10W30.

[CMNTMXR57]

As above, the only difference is viscosity when cold. A 5W oil will flow better when cold vs. a 10W. Hence why a 5W is a better choice in a colder climate.

Otherwise, it will boil down to individual brands you chose. But for example purposes, say a Valvoline 5W-30 is the same as a Valvoline 10W-30, in terms of base stock oil, additive (detergents, anti-oxidizers, anti-foam agensts, etc), just the viscosity difference when cold.

[00Beast]

Use what the manual says to use, unless you live in an extreme climate (IE: Northern Canada or Death Valley). Since I'm guessing you don't, 10W-30 is fine for you. My 03 calls for 5W-30 because of a change in parts in the oiling system sometime in 2002, IIRC, so I run 5W-30.

[DaMaroon]

Below is the way my 03 SE manual says it. Where I live 1OW-30 is good for all but 2 weeks in an average year. 5W-30 shouldn't be used ~ 6 months. OW-30 could be used about a week out of the last 30 years. Follow you're manual's recommendations for where you're driving, when practical.

"SAE 1OW-30 is the viscosity grade recommended for
your vehicle. However, you can use SAE 5W-30 if
it’s going to be colder than 60°F (16°C) before your next
oil change. When it is very cold, colder than 0°F
(-18°C) you should use an SAE 5W-30 oil. These
numbers on an oil container show its viscosity,
or thickness. Do not use other viscosity grade oils, such
as SAE 1OW-40 or SAE 20W-50 under any conditions

Notice: Use only engine oil with the American
Petroleum Institute Certified For Gasoline Engines
starburst symbol. Failure to use the recommended
oil can result in engine damage not covered by
your warranty.

If you are in an area of extreme cold, where the
temperature falls below -20°F (-29°C) it is
recommended that you use either an SAE 5W-30
synthetic oil or an SAE OW-30 oil. Both will provide
easier cold starting and better protection for your engine
at extremely low temperatures."

[nubuilder]

Use what the manual says to use, unless you live in an extreme climate (IE: Northern Canada or Death Valley). Since I'm guessing you don't, 10W-30 is fine for you. My 03 calls for 5W-30 because of a change in parts in the oiling system sometime in 2002, IIRC, so I run 5W-30.

Hmmm..... I thought my car was a late '02 due to the Monsoon system. My oil cap says 10W30, but now you have me wanting to read the manual.

Would it be bad to run 10W30 in the winter?
I just don't know if I'll get another 5-7k on my car before the end of November (running Mobil 1).

[2003 SSEi]

Use what the manual says to use, unless you live in an extreme climate (IE: Northern Canada or Death Valley). Since I'm guessing you don't, 10W-30 is fine for you. My 03 calls for 5W-30 because of a change in parts in the oiling system sometime in 2002, IIRC, so I run 5W-30.

actually the change didnt happen untill 2004 with the Series 3. And the Change was for increased fuel milage. All the oiling system parts are the same in the S2 and the S3. The only difference is the front cover being Sand Cast in the S3 that has been known to restrict oil flow.

My 03 calls for 10W-30, however I run 10W-40 because its only driven in the summer and ususally sees higher oil temps (aka at the track) This provides better oil pressure in the extreme temps. However my car is modified, and this is not for everyone

[2kg4u]

Would it be bad to run 10W30 in the winter?

I run 10W30 year round.

[00Beast]

Pat, I'm curious, what is the build date on your car? The cap on my car said 5W-30 when I got it, I never checked the manual. My car was built 1/28/2003. I wonder if the change didn't happen mid-03?

[crash93ssei]

My 03 is 5w30 also.

[CMNTMXR57]

You can run whatever you want technically. Winter, spring, summer, fall.

The difference is, a 10W won't pump up/flow and lubricate cold parts in cold weather as quickly as a 5W will due to that viscosity. That's all.

AS to what's on the cap, that is just a cap. Sometimes based on delivery destinations little things like that can happen. If a car was purchased by a dealer in Alaska, probably had a cap with 5W-30 on it. If it was one purchased in Death Valley, CA, it probably came with a cap saying 10W-30. Cars move around, dealers do swaps, caps get replaced, people move to different regions, etc, etc...

I will say, here in Chicago, in service, I could probably count on my fingers, the number of cars I saw with oil caps that said "10W-30" on them.

Regardless, read your manual, use what works best with your climate.

[00Beast]

What I find is weird, because my car was a FL car.

[myxocai1965]

Manual says to use 10w30. Is the engine better protected with this grade of oil?

I use 5/30 in the winter months, for easier starts and 10/30 in the summer.

[nos4blood70]

The cap on my car says 5W30. But she's seen 10W30, 5W20 all without problems.

[Jrs3800]

My 03 is 5w30 also.

My 03 is also 5w30

[2003 SSEi]

Pat, I'm curious, what is the build date on your car? The cap on my car said 5W-30 when I got it, I never checked the manual. My car was built 1/28/2003. I wonder if the change didn't happen mid-03?

I was built 10/16-20/2002. 10W30 on the oil cap

[00Beast]

Ahhh. I wonder if there wasn't some changeover mid-03. Be interesting to know...

[Jrs3800]

My car was March 03 iirc...

[Jrs3800]

The cap on my car says 5W30. But she's seen 10W30, 5W20 all without problems.

Whats the Build Date Carl?

[nos4blood70]

Late May 2003.