another oil question

[mr. ed]

I use Valvoline 10W-30 synthetic oil in my 2000 Saturn SL-2. The preferred oil is 5W-30, although the book says 10W-30 is OK as long as the ambielt temp doesn't get too low. I do feel more comfortable with the 10W-30, although I realize today's engines are engineered for the lighter stuff.

So, my question: is there any benefit to be gained (engine longevity) by using the heavier oil? (I am virtually never in below freezing temps). I realize there will be a slight gain in gas mileage using the thinner oil, but I'm more interested in engine protection rather than gas mileage...it's already very good. What say you?

Mr. Ed

[92saturnsl2]

Both oils are multi viscosity. When the engine warms up and the oil gets hot, they are essencially the same weight and thickness...

5W when cold, 30W when hot.

It is safe to use either as long as temps dont go below 0 degrees, then 5w-30 is required...

With wintertime ahead, I'd go with the 5w-30 as the engine will have an easier time starting, and less start-up wear due to quicker lubrication on startup (thinner oil).

Conventional (dino) oil uses hydrocarbon chains and paraffin (wax) to achieve their multi-viscosity trait.

So for example, 5W-30 conventional will break down faster (compared to 10w30) due to longer hydrocarbon chains (to acheive such a wide viscosity). This causes sludge buildup, not a good thing. This is common in oils like 5w30, 10w40, 10w50, while 10w30 this is generally not as much a problem.

So if temps are good, 10w30 may have a slight longevity advantage, but the tradeoff is the thicker weight when the oil is cold.

Probably wont notice and difference in gas mileage between the two oils.

Thumbs up for using synthetic, but if prices are comparable, go with Mobil1 as it's the only (store sold) PAO "true" synthetic. Valvoline, Castrol, and the like, use a cracked conventional base oil. Mobil1 is the real deal.

[ym42]

What about this new stuff 5W-20?

[jabinns]

Originally posted by ym42
What about this new stuff 5W-20?

ym42, 5w20 is too thin, not designed for saturns. every bottle of 5w20 says make sure that your manufacturer recommends it. my 2002 Honda CRV recommends 5w20 (i've fought with them and they said if I use 5w30, they will not cover warranty on engine problems), and I relunctantly use it (atleast until I hit 3yr/36,000 on it). there is only one synthetic for it (at stores anyway) and that is motorcraft synthetic blend 5w20. mobil1 told me their 5w20 full synthetic will be coming out in jan or feb of 2003. anyway, the oil is meant for better gas mileage and fast protection during cold cranking. the oil pressure in your saturn may not respond the same to a thinner oil than is recommended. it may come out in the end that it is ok to use, but i would not recommend it. besides, you can only find two dino types (castrol, pennzoil) and one cracked blend (ford motorcraft), so you really dont have any good choices until mobil1 is done doing their perfection of it.

[dieseljack]

My 2002 RSX has the same 5W-20 requirement. The "S" type calls for the 5W-30, but Acura insists on the 5W-20 in the base model. This is with a 10,000 mile change interval, with 5000 miles for extreme conditions. They also require that the break-in oil be kept in for the full change period. With a standard 50,000 mile warranty, I guess there's no point in arguing.

[manualman]

Dieseljack bought a Honduh!?!

Normally I would hassle you for that, but I just got my wife an Odyssey, so I'll shut up now.

Are you really gonna use 5w20? The 3.5 in the Odyssey (and soon in the VUE) requires it, but I'm suspicious that they care more about their gas mileage rating than about making the engine last 200,000 miles.

A lot of the folks on Odyssey forums are using 5W30 and no trouble so far. I'm inclined to go 5W30, but I've got 2,000 miles before I have to decide... Maybe I'll use their 5W20 for the first 20k miles to get a bit of wear first.

[wolfman]

Just out of curiosity, how exactly would the dealer know what brand/viscosity of oil you are using unless you told them? Somehow I doubt they'd shell out the time and money for an oil analysis.

[jabinns]

If you dont have any records showing that you changed the oil with 5w20, then you are as good off showing that you used 5w30. I have copies of the receipts for the oil and the filters that I buy, and the dates and mileage of the change (I dont let anyone else change my oil). If you cant prove that you changed the oil with what they recommend, then in their eyes, you didnt.

[bbriand]

Ok so whats up with the zero weight synth oils? I was shopping for 5W-30 and saw 0W-30. Would that be better to use? Also can we go higher on the second number, say 5W-50?

Bill

[jabinns]

I would stick with the 5w30 unless it gets below -40 where you live. The 0w30 just pours/pumps at a lower temp than the 5w30, but not that much lower. You dont want to go with the 5w50 because its operating temp weight (50w) is too high for the saturn.

[93BLKTWINCAM]

Originally posted by 92saturnsl2
Both oils are multi viscosity. When the engine warms up and the oil gets hot, they are essencially the same weight and thickness...

5W when cold, 30W when hot.

It is safe to use either as long as temps dont go below 0 degrees, then 5w-30 is required...

With wintertime ahead, I'd go with the 5w-30 as the engine will have an easier time starting, and less start-up wear due to quicker lubrication on startup (thinner oil).

Conventional (dino) oil uses hydrocarbon chains and paraffin (wax) to achieve their multi-viscosity trait.

So for example, 5W-30 conventional will break down faster (compared to 10w30) due to longer hydrocarbon chains (to acheive such a wide viscosity). This causes sludge buildup, not a good thing. This is common in oils like 5w30, 10w40, 10w50, while 10w30 this is generally not as much a problem.

So if temps are good, 10w30 may have a slight longevity advantage, but the tradeoff is the thicker weight when the oil is cold.

Probably wont notice and difference in gas mileage between the two oils.

Thumbs up for using synthetic, but if prices are comparable, go with Mobil1 as it's the only (store sold) PAO "true" synthetic. Valvoline, Castrol, and the like, use a cracked conventional base oil. Mobil1 is the real deal.

Good and accurate info. I was around when Mobil 1 first hit the retail market and it has become very cost-effective. A FYI item...Mobil Synthetic had a recommended 25,000 mi. recommended oil change interval, but removed the text from the back of their bottles...I imagine libility issues...

[OhioVueBoy]

Our Mercedes requires something stupid like 0w40. The only car I have seen that requires 10w30... well anything with a GM 3800 in it, like our Monte Carlo... which is for good reasoning... the 3800 tends to get a noisy upper valvetrain at high mileages, and needs high oil pressure to run properly.. thats why many people / mechanics recommend replacing the oil pump in a 3800 every 100K miles.
Hmm... yea... lets see...for our vehicles we require
5w30 (Truck, VUE)
10w30 (Monte Carlo)
0w40 synthetic (Benz)
20w40 (Boat)
SAE30 (Lawnmowers)
Not to mention 3 different types of 2 cycle oil for the Jetski, blower, and weedeater.
whew... our garage looks like a veritible AutoZone.
~D.J.~

[adelyser]

Originally posted by 92saturnsl2
Both oils are multi viscosity. When the engine warms up and the oil gets hot, they are essencially the same weight and thickness...

5W when cold, 30W when hot.

It is safe to use either as long as temps dont go below 0 degrees, then 5w-30 is required...

With wintertime ahead, I'd go with the 5w-30 as the engine will have an easier time starting, and less start-up wear due to quicker lubrication on startup (thinner oil).

Conventional (dino) oil uses hydrocarbon chains and paraffin (wax) to achieve their multi-viscosity trait.

So for example, 5W-30 conventional will break down faster (compared to 10w30) due to longer hydrocarbon chains (to acheive such a wide viscosity). This causes sludge buildup, not a good thing. This is common in oils like 5w30, 10w40, 10w50, while 10w30 this is generally not as much a problem.

So if temps are good, 10w30 may have a slight longevity advantage, but the tradeoff is the thicker weight when the oil is cold.

Probably wont notice and difference in gas mileage between the two oils.

Thumbs up for using synthetic, but if prices are comparable, go with Mobil1 as it's the only (store sold) PAO "true" synthetic. Valvoline, Castrol, and the like, use a cracked conventional base oil. Mobil1 is the real deal.

First, to start with oil that is 5W when cold and then thicken to 30W when warm is completely against the laws of physics. You must understand what the numbers on bottles of multi-viscosity oil mean to determine which is best for your use.

The first numbers, 5W, 10W, 15W, or 20W are the base weight of the oil. 5W-30 oil is 5 weight oil, and 10W-40 oil is 10 weight oil.

The second set of numbers determine how much the oil thins when warmed. 5W-30 oil is 5 weight oil that will only thin as much as SAE 30 oil will when warmed. 5W-50 oil is still 5 weight oil, which will have very similar properties to 5W-30 when cold, but it only thins as much as an SAE 50 oil will when warmed. This means that when the engine is warmed up, the oil won't be as thin as 5W-30, but the difference is actually quite minor.

10W-30 oil is a good bit heavier than 5W-30, and will be heavier than 5W-50 when warmed, because the oil is twice the weight to start with when cold. 10W-30 oil will provide better protection from wear compared to 5W-30, but will also result in decreased gas mileage and performance. Most manufacturers suggest 5W-30 or even 5W-20 in newer cars to get their gas mileage numbers up.

[92saturnsl2]

5w-30 oil is a 5 weight oil which will not thin more than a 30 wieght oil would when warmed....

Much like a 10w-30 oil is a 10 weight oil which will not thin more than a 30 weight oil would (just like 5w-30)..

These are the two oils the thread is talking about

When the engine is warmed up they BOTH will not thin more than a 30 weight. Just because they start out 5 or 10 weight doesn't mean they are different weights when warmed up. The last number holds true for all weight oils..:

20w-50 starts out 20w, wont thin more than a 50 weight oil would...
10w-40 starts out 10w, won't thin more than a 40 weight oil...

well you get my point by now...

So I don't see how 10w-30 would protect the engine any better than a comparable 5w-30 oil in the same conditions.

Besides the fact of longevity, the longer hydrocarbon chains in 5w-30 will break down (shear) faster than the ones found in 10w-30.

http://www.vtr.org/maintain/oil-overview.html
A little food for thought....

[adelyser]

I don't think you are understanding the numbers completely. The second number doesn't indicate what the oil will be when warmed, but how much the oil will change when warmed. Since both 5W-30 and 10W-30 oils have the same 30 rating, they both will change the same amount. The 10W-30 oil starts heavier, and when warmed, will still be heavier.

I have run both oils, and when draining the oil, it is quite easy to notice that the warm 5W-30 drains a lot faster than the warm 10W-30.

I agree that 10W-30 oil will last longer. That is probably why many manufacturers are recommending 5W-20, as they will last longer.

[92saturnsl2]

Where are you getting your information?

The Society of Automotive Engineers (SAE) has established a scale which indicates oil thickness (viscosity). SAE numbers include, for example, 10W-30, 5W-40 and sometimes just a single number such as 5W, 10W, 20, 30, 40 or 50. The "W" next to a number means the oil thickness was measured at a cold temperature, usually 0 F. A number without a W suffix indicates the oil thickness was measured when the oil was hot (210 degrees F).

A multiviscosity oil such as a 10W-40 will function like an SAE 10W (10W measured differently than standard SAE10 of course) oil at cold temperatures and like an SAE 40 oil when the temperatures are warm or hot.

I have checked dozens of websites, and FSM's.

http://www.bre.umd.edu/fact181b.htm
http://www.autoeducation.com/autoshop101/oil-change.htm
http://www.vtr.org/maintain/oil-overview.html
Above are a few.
http://www.csaa.com/global/articlede...7C2024,00.html

Please feel free to provide links/sources to any info..

[adelyser]

Ok, it seems I was the one misunderstanding the information. Most of the information on the internet, to include your 3rd link don't specify the indication correctly. What I keep on finding is that most documents state something similar to: 10W-30 flows like SAE 10W oil when cold and only thins as much as a SAE30 oil would when warm.

The phrase "only thins as much" means that if an SAE30 oil becomes 40% thinner when warmed, the SAE10W oil will thin no more than 40%. This includes your description in your posts above.

I have found a couple of sources that do state it correctly. I have read a couple that state: An SAE 10W-30 oil is within the specified limits at -18 C for the SAE 10W grade, and yet at 100 C its kinematic viscosity is that of an SAE 30 grade. This statement is much clearer to me, and I now completely understand.

So as you stated earlier, 5W-30 and 10W-30 should be the same thickness when warm.

In one of your first posts, your statement that 5W-30 oil is 5W when cold, and 30W when warm is actually incorrect. I think you meant that the oil is 5W when cold, and SAE30 when warm. Just for everyone's info, the W in 5W indicates the viscosity was measured at very cold temps instead of the warm temp measurements like SAE 30.

Sorry for the incorrect info, but thank you for shining the light!

Adelyser

[92saturnsl2]

Yeah I agree the first post (and some subsequent) could have been worded different. It had been a long time since I researched the information, and didn't really have it on the top of my head as to wording it.

I think the conclusion here is in winter stick to 5w-30 (where you're much better w/ synthetics IMHO), and 10w-30 in the summertime.

If ambient temps run above 50 degrees, there is minimal difference in startup protection between the two oils. Anything colder and I'd rather be protected by the thinner oil an startup (where the majority of wear occurs in an engine)