What Oil Should I use?

[RandomFact314]

I have a 2000 Dodge Neon. The recommended oil is I think 5W30 (Which is what I use) I have been using conventional but I have started using a little bit of synthetic and plan on converting completely to synthetic. The temperatures here are usually around 70* F (21.1*C) but range from 30* F (-1.1*C) in the winter to 100* F (37.7*C) in the summer. What should I use if I use conventional and what should I use if I use full synthetic?

[theunchosen]

Synthetic 5w30. . .lol?

All the brands are about the same. If you are feeling a little chancy you might mix in a little 5w20. The lighter weight will create less resistance in the cylinders.

I'm sure this is true lol. I had to put some high performance pistons in a D15 the other day and I couldn't make the piston go using 30w, but I squeezed it in with 15.

Be warned. It may cause the engine to leak the lighter oil. I doubt it but it might happen. Also warning. If you go too light it might burn up the light oil before heavier oil can take its place.

Depends on how hot your engine gets. If it gets really hot a heavier fluid is probably best. If it stays very cool(sub 200) you might be able to go with a lighter fluid.

[RandomFact314]

Originally Posted by theunchosen

Synthetic 5w30. . .lol?

Am I missing Something, why is that funny? Its Pennzoil Platinum Full Synthetic 5W30.

[theunchosen]

I was just covering my bases unless you were asking what weight synthetic should you use after switching off of conventional.

Like I said. . .brand doesn't mean a whole lot unless you are running the engine like a bat out of hell.

So unless you come sliding sideways out of your driveway with wheel spin in the morning. . .it doesn't matter.

I work for an auto garage (a shop as I refer to it lol) and we throw whatever is cheapest in there. There really isn't a whole lot of difference for the most part. They like to say there fluid does this or that better but its really just a bunch of hand waving. . .

[evolutionmovement]

I'd agree there's probably not much difference, but I use Mobil 1 FWIW. Tearing down a Subaru EJ22 at 250k miles of being driven like a race driver's rental car revealed little sign of use. All cylinders were crosshatched nicely, main bearings looked good for at least another 100k, and the cams and rockers showed little sign of even being used at all. All but the first 100k miles were with Mobil 1 so I've stuck with it. But I would think any other synthetic brand would also do as well.

[ratherbehiking]

I just switched to a lighter weight full synthetic from a conventional. Before the switch I had a very small oil leak, that oil leak is now a bit more noticable so be warned, if you switch to a lighter weight oil you might find some leaks you didnt know about.

[RandomFact314]

I never said that brand makes a difference, I don't even know where that whole thing started, Was it when I said "conventional", When I said that I meant "normal" oil, opposed to synthetic.....So ANYWAYS is going down from a 5W30 Normal Oil to 0W20 Synthetic too much of a difference is what I'm trying to get at here?

[evolutionmovement]

I wouldn't bother with 0W. Stuff pours like water it's so thin and will find places to leak from. Also, the 0W doesn't protect as well at high temps as 5W/30 and is, IMO, unnecessarily overkill low for cold temps. If you were going to change at all, you'd be better off going to 10W/40 for the summer than 0/20, but the 5/30 is probably the best all around choice. What does the owner's manual recommend?

[jetta2.5L]

yes the new 0w-30 kinda scares me theres fuel savings but that dont help if your engine wear comes faster...when i was running a 06 saturn ion i used 5w-30 mobil one extended life i drive around 30-40k miles a year mostly highway and it hasnt changed wish it would none the jetta i drive now because of it being 5w-40 my choices are limited if i want good engine life and fuel economy i go with shell rotella T (very good oil no horsepower) since iam a speed demon i go with the factory oil castrol syntec very good oil gives the engine life and the mpg is pretty good....

...another to check out my buddy uses royal purple and amsoil he swears by them ...beats me iam perfectly happy with syntec!

[stevey_frac]

Originally Posted by evolutionmovement

I wouldn't bother with 0W. Stuff pours like water it's so thin and will find places to leak from. Also, the 0W doesn't protect as well at high temps as 5W/30 and is, IMO, unnecessarily overkill low for cold temps. If you were going to change at all, you'd be better off going to 10W/40 for the summer than 0/20, but the 5/30 is probably the best all around choice. What does the owner's manual recommend?

Ow30 is exactly the same viscosity when warm as 10w30. Furthermore, the fact that it's lighter when cold IMPROVES wear. Engines are designed around a certain operating temperature and oil viscosity. When the engine is cold 10W30 is about 5-6 times too thick. The oil pump has a much harder time pumping this very thick oil around and flow suffers. Your oil PRESSURE is probably fine. But oil flow is severely limited.

Real values of real oil. (Amsoil used because they publish it all if you know where to look, not because i'm a fanboy)

AMSOIL 0W30 SSO

Kinematic Viscosity @ 100°C, cSt (ASTM D445) = 10.3
Kinematic Viscosity @ 40°C, cSt (ASTM D445) = 56.6


AMSOIL 5W-30 ASL

Kinematic Viscosity @ 100°C, cSt (ASTM D-445) = 10.8
Kinematic Viscosity @ 40°C, cSt (ASTM D-445) = 60.7

AMSOIL 10W-30 ATM

Kinematic Viscosity @ 100°C, cSt (ASTM D-445) = 10.7
Kinematic Viscosity @ 40°C, cSt (ASTM D-445) = 62.0


(note, the cold numbers only get worse as it gets colder)

People mistakenly believe that the problem with oil is that it thins as it heats up. This is a really the wrong way to look at it. The problem with oil is that it thickens as it cools! Most engines are designed around a 100C or 212F operating temperature. Your oil will stay at around this temperature unless your drag racing it once it has warmed. Until the oil heats up though, your pumping this very viscous fluid around, and it's probably 6 times too thick. It's have a hard time reaching all the parts of your engine in sufficient quantities to be useful. You wouldn't reccomend someone run an SAE 150 oil would you? But this is more or less what your doing every time you start your car from cold. It's also one of the reasons why most wear occours during cold starts.

This is why most engines now use 5W30 instead of 10W30. The only reason these engines don't get back-spec'd to a 0W30 oil is because it can't be done properly with a conventional oil at this point, so 0W30 oils are synthetic and expensive. Run a 0W30 oil. Your engine will like it. Your fuel economy will like it.

Complaints that it 'pours like water' and that 'it'll find new places to leak' are unfounded, and unreasonable. Even 0W30 is 5 times to thick at 40C for the engine. It's just closer to 'normal' then 10w30. They are ALL the same thickness at operating temperature, and all provide similar levels of protection.

I would caution you against putting a xw40 oil in your car. Unless your driving like a bat out of hell, or pulling a trailer through death valley, or your commute involves climbing pikes peak at 70 MPH, it's going to be too thick even when warm for your car. Not by much, but still too thick. Roughly 50% thicker then design spec for most cars.

AMSOIL XL 10W-40

Kinematic Viscosity @ 100°C, cSt (ASTM D-445) = 15.7
Kinematic Viscosity @ 40°C, cSt (ASTM D-445) = 104.4


Now... when your cold starting that 10w40. It's going to be more then 10 times too thick! You would end up accelerating wear (significantly, but not catastrophically) and ruining your fuel economy. The only logical argument i've heard for running these thick oils is if your main bearings are worn badly enough that they literally hemorrhage oil, and the thicker oil prevents this somewhat, and allows your car to maintain oil pressure despite this. This prevents oil starvation of the top end, and is desirable.

EDIT: Re 0w20

It's a touch thin, but not terribly so.

AMSOIL 0W-20 (ASM)

Viscosity @ 100°C, cSt (ASTM D-445) = 9.0

If your hypermiling i'd be inclined to think that you'd be ok. That being said, I wouldn't do it, mostly because i'm conservative about that kind of thing.