Lone Ranger

In a recent thread someone said to what ever you do "get that 5W-30 out of your car" to another member, something about 5W-30 being bad and 10W-30 being better because of something to do with 'plasticizers' in the 5W-30 or similar compound(s).

Can anyone clear this up?

I'm running 5W-30 Mobil 1 and that is what the badge under the hood from GM proclaims to be preferred.

Not trying to spark a big oil debate, just want to know if there is something peculiar about 5W-30 I should understand before using it.

Southern Comfort

10W-30 Just feels better, dont ya think :thumbs:

And heck its the same price.....what a deal :steering:


[Modified by Southern Comfort, 1:16 PM 7/6/2003]

Lone Ranger

:confused: <scratches head>...

REW89

In my opinion the weight of the oil is directly dependent on the particular climate. Owner's manauls usually give you a range of temperature conditions and a recommendation on weight for those conditions. I think for service in colder climates you will find your manual may recommend 5W-30 while for warmer climates 10W-30 is recommended.

Since I live in the South and my vert stays garage most days in the winter, 10W-30 seems to work just fine for me. My 89 has 57K miles and does not use a drop between changes and operating temperatures and pressure always seem to be satisfactory.

MTCW Bob

Southern Comfort

Ranger,
Seems to me if your car runs ok on what you have in it....stick with it. I just switched from dino to Mobil 1 10w-30 and I have 153k....seems to be doing ok. I did notice that my oil tems went up a little quicker than before, buts its been 110 degrees here so who knows.

vader86

5w30 is like water on startup, its very thin and allows the crank to move very freely. It should be used in cars that see use in colder climates year-round.

10w30 would be better for summertime, just about anywhere in the U.S.

The only reason I didnt put in 10w at my last change was because the shop didnt have any, they only had 5w. I also drive her once or twice a week in winter, so I stick with 5w30 for that.

Once they both get hot, both run 30w viscosity, the difference is in cold starts.

No Go

It doesn't matter! :)

I only run 5W30...car never sees winter, but it does 300 degree on the track in 95 heat. 83,000 miles too.

NOT-MEE

Im running 15/50 mobil 1 and so far soo good it has been really hot here and i sit in lots of traffic so my temps were soring,so i changed to 15/50 my temps stay down better and i drove to the 50th and e sat in traffic for over a hour and my temp never went over 220 deg and it colled quickly.Im running a 160 stat so my temps stay around 180.My pressure came up a few pounds 28#'s hot idle 38#s cold idle.48-53# running on freeway.I switch back to 10-30 in winter.

Alex D

This argument is pretty useless..........I talked for soemtime to M1 and Redline techs on the phone....... because 5w30 and 10W30 only differ in cold viscosity (40F)....they are identical in hot viscosity (200F)......so there is no advantage in running 10W30......you have to move up to a 10W40 or 0W40 to get increased hot viscosity.......M1 provides all of these viscosities.....15W-50 is pretty darn thick when cold so I would not run it in the winter or when colder than 60F.........to take advantage of higher hot viscosities you really need to run the engine very hard, like autoX or prolonged high speed operation....(aka Autobahn)......both M1 and Redline both advised against using higher viscosities in regular driving ........they are fine up to 300F oil temp........


[Modified by Alex D, 8:23 PM 7/6/2003]

linkschamp

:iagree:

So does GM! (check your owners manual and see)

MagikDraggin

I hope I don't sound like I actually "know" what I'm taking about here, but I did read where the larger the difference between the numbers in multi-viscosity oils, the more "protective" agents the oil companies must leave out of the oil in order the achieve the multi-vis properties. "Plasticizers" may be the correct word but I have no idea what they are.

In other words, 5/30 is not as good at protecting an engine under extreme conditions than 10/30 is. For maximum protection it was recommended to run a straight weight oil in temps above 80° F. and for extended high speed driving. I also recall reading where Mobile 1 is not a "true" synthetic oil, for what it's worth, being more of a 50% synthetic blend.

Karl

Mike_88Z51

Lone Ranger,

What I believe you refer to are "polymers". Check out this site for real info that should help answer your question. http://www.unofficialbmw.com/all/misc/all_oilfaq.html The author in my opinion, is a bit prejudiced towards Amsoil, but his facts about oil in general are true and based upon SAE standards.

There is a belief that using an oil which has the narrowest range of viscosity values is the absolute best oil to use. Like many beliefs based upon truth this one has been twisted a bit. If you go to the site above you will see that the author states "Always use a multi grade with the narrowest span of viscosity that is appropriate for the temperatures you are going to encounter." This is based upon the belief that a narrower viscosity range oil has fewer added polymers which allows for more of other useful additives and longer service life of the base oil. While this is generally true, the author admits "Mobil 1 uses no viscosity improvers in their 5W-30, and I assume the new 10W-30." If this is correct about both Mobil 1 oils, then the use of 5W-30 versus 10W-30 is not a choice to be made based upon viscosity range, since there is no "added polymers" penalty for a larger range with these two specific oils.

In fact, what the author has stated that he really knows is that the 5W-30 Mobil 1 has no need for added polymers and he "assumes" that the 10W-30 doesn't either. This may be incorrect and the 10W-30 Mobil 1 may indeed need additional polymers to bring the base weight to 10W. ( I'm not saying it is so, just that it is possible). Why would Mobil do this? Well for marketing reasons for one. If people believe 10W-30 is better than 5W-30 they are less likely to buy 10W-30 from another oil manufacturer.

If his assumption i correct and there is no difference in base additives then how to choose? The author suggests "Always use a multi grade with the narrowest span of viscosity...", which is what a lot of people regurgitate as fact without considering that there may be other conditions to consider. Remember that the 5W oil will flow more easily than the 10W oil at startup. As the author states" An oil with too high a viscosity may not pump to the proper parts at low temperatures..." Depending on an engine's internal clearences and tolerances the oil that flows most freely with appropriate shear strength is usually the best choice. The easier it flows the less work is needed by the engine to move it, meaning more energy used to turn the driveshaft. That is why the 5W-30 oils generally carry an "energy conserving" seal on the container.

So which is better? Well, for some odd reason I belive a bunch of highly paid, highly skilled engineers at GM probably know more than most back yard mechanics so I follow the suggestions supplied by GM. As long as GM Corporation will warrant a new Corvette engine for thousands of miles using Mobil 1 5W-30, I'll stick with the freer flowing oil.

zog

I agree with Mike:

"So which is better? Well, for some odd reason I belive a bunch of highly paid, highly skilled engineers at GM probably know more than most back yard mechanics so I follow the suggestions supplied by GM."

I run 10W30 in my'86 because it has 98,000 miles on it and I don't know what the bearing clearances are like...I have no idea what the previous owner used or how ofen the oil was changed. It runs great and uses no oil, but if I ever have to rebuild it, I will opt for th 5W30...I trust the GM engineers...after all, they designed the Corvette!!!! :auto:

Jeffyvette

I have it on a good source (I have to leave unnamed, so I don't get kicked off this forum, due to their differences of opinion) that 10/40 is best overall. But Mobil 1 does not come in that weight. So mix 5/30 and 15/50 50/50 mix persto 10/40. In the race car I use Torco brand, but at $12/QT it is a little steep.
Jeffy'

Strick

I think I Mobil 1 is 100% synthetic. I have an article written back when Mobil first introduced Mobil 1. It was in Popular Science or Mechanics Illustrated and it talked about Mobil 1 vs petro (dino) oils. They mentioned the simularities to synthetic oils used in jet engines.

Now, most other synthetic blends mislead you in their labeling like Syntex. All oils claiming to be synthetic are not equal.

Anyway, since that article, I've used Mobil 1 in all my cars and I have been very satisfied. Couple that with what the Corvette designers recommend, it's nothing else in my Vette.

Now to the original question, 5W-30 vs 10W-30, I live in SC and it gets hot so I use the 10w-30, it's in my manual. If I plan to drive in the winter (which doesn't happen very often), I'd use 5W-30. Keep, It, Simple, Stupid (KISSmethod). :yesnod:

Rick93Z07

If you road race for 30 minute sessions or drive the Arizona desert at WOT, choose 10W-30. If your car sees lots of cold starts (under 150 degrees F ambient), your motor will most definitely see LESS wear with 5W-30.

It's a tough decision. Either way, your motor will last 300K+ miles on any quality API full synthetic of recommended viscosity.

85 Dave

What difference does this make? Both oils are a 30 weight at operating temperature.

Mobil 1 does not uses polymers to modify the base oil to achieve the 5w30 rating. Dino oil uses polymers to get the 5w30 rating. Polymers do not protect or lubricate as well as the base oil, therefore with Dino oil, the 10w30 would be a more stable, better lubricating oil.

If using Mobil 1, use the 5w30. And Mobil 1 is 100% synthetic.

John Row

:iagree:
Why is this a hard concept?

Davemc1963-87conv

Mobil 1 also comes in 0W/40. Maybe this solves everybodies problems. Thin when cold and "heavier" when hot. :reddevil
With the above thrown in the pot for a bit of interest, I will say, that I have used 5W/30, 10W/30 and 10W40 with no problems. However with a higher mileage engine, oil pressure will be less than a new one, and increasing the "hot" viscosity rating of the oil should bring oil pressure back up a little.
However, at what point an engine becomes a "high mileage" engine is open to interpretation.
:steering:


[Modified by Davemc1963-87conv, 9:04 PM 7/7/2003]

Lone Ranger

:skep: