I see no issue with 30psi at idle (and the occasional dip to 25ish when sitting in traffic with HOT outside temps), for an A4 car with a 550rpm idle speed in gear. 40-45psi is not necessary. Just as 60psi is not necessary at 2000-2500rpm cruise speeds.

I'm more concerned with pressures as the rpm rises than at idle. I don't really care if I make 30 psi at idle or 45psi at idle, what would concern me more would be something like only 50psi at 6000rpm.

 

 

So your saying M1 5w40 is good for the LS1?

 

And i dont think Ive ever seen an LS1 make that low of oil PSI at 6K due to the type of oil used.

 

i'm just saying a feel more comfortable with a 40 psi at idle. with GC, my oil pressure never dipped below ~45 psi, even when it got hot. it always stayed constant. it's just a better (albeit heavier) oil than anything mobil 1 makes.
yes, M1 5W-40 is probably the best oil under the mobil 1 brand you can get for the LS1. that is my opinion, and UOA's back me up. it's good, but i just feel GC is a better performer from what i have seen so far.

 

Dan, I got a really good UOA with M1 5w-40 TrSuv. The new version is the same weight but is called something like Turbo Diesel. The numbers were squarely within GC quality range. I would have no trouble using it simply for that reason. My consumption of it in my LS1 was < .5qt per 4-5k miles. I don't consider that bad, and it doesn't even move the needle on my Concern-O-Meter.

Choco, at any given time 6 qts or 5 qts is sufficient to oil your motor. As long as the galleries are filled and there's enough in the pan to prevent cavitation at all rpms and movements, there's enough. It takes more than bare minimum, however, to last through the entire oil change interval and still have a quality oil coursing through the motor's galleries. Oil changes composition and accumulates nasty bits over time, and a larger sump means less total change over that time. Five qts is .5 qts down from factory recommendation and doesn't appear to have caused any undesireable changes to a degree that causes concern in any of the UOAs I've seen and remember.

At the bearing wear surface, parts are separated by a wedge of oil that builds up with movement. It develops as long as there is sufficient oil to maintain it and the oil is within a range of viscosity that neither allows it to be wiped off or simply not develop by too thick of oil nor to be squeezed out by too thin of oil. Either condition allows metal to metal contact.

Pressure is not the only consideration. I think we all agree that pressure for pressure's sake is a fool's errand. Pressure is not what keeps the parts from making contact. As long as there is sufficient pressure to deliver oil it should be able to allow the bearings to present the proper oil wedge at the (non-)contact surfaces. As long as the motor does not have excessive clearances it should be able to maintain a sufficient oil pressure. The big and important consideration is oil flow.

Oil flow, I think, is more important than oil pressure. Higher oil pressures does not mean more flow, it means resistance to flow. Think of a kink in a garden hose...higher pressure but not higher flow. Alternately, consider how much water would be delivered through that garden hose versus how much honey at any given pressure. An extreme and crude example, I know, but illustrative.

Flow of oil, though at a lesser pressure, bathes the bearings and wear surfaces in more total oil per unit of time than does pressure. The wedge of oil will still develop, and there will always be a more than sufficient amount of oil bathing the surfaces to keep it going. More oil flow means more dirt is taken away to the filter. More oil flow on hot parts means more heat is removed and taken to the oil cooler. As long as the oil is of sufficient viscosity to maintain the oil wedges at the wear surfaces, I don't see how more flow over more pressure is a bad thing.

I think it would be a good thing, also, to not get caught up in 0w vs 5w numbers. Again, as the oil viscosity chart shows, there is a huge range of 40*c viscosities within the 30w and 40w ranges. M1 0w-40 40*c viscosity is 80.0. GC (0w-30) viscosity is 66.8. Alternately, 5w & 10w-30's range from 58.8 to 79.1. It is simply not accurate to generalize that 0w is "too thin," when they can easily be of thicker viscosity than other 5w's.

But most importantly, I must counter your declaration that thin at startup is a bad thing, and that it isn't important since it spends so little time there. Oil flow at startup is very important, as that is where most of the wear occurs. Between the time of dead stop to when the oil wedge develops you are dependent upon whatever oil remains at rest and the beginning of the flow of oil. Thinner oils flow to moving parts faster than thicker oils. It's as simple as that.

And, again, I think GC produces its outstanding wear numbers not because of its inherent viscosities, but because of its composition. There are any number of oils that produce the same pressures but none work as well in our engines.

 

Mr Incredible,

An excellent post on oil and the nature of oiling, as usual.

 

Thanks, Rpm. It's a satisfying feeling when it starts to come together. Each old wives tale and oil myth I shed makes me feel like there may yet be hope. The search for knowledge never ends, though.

 

nothing i said is a wives tale. the GC outperformed the mobil 1. an example of a wives tale is that mobil 1 is this great oil head and shoulders above everyone else. most of their oil is a group III and it's so thin, it's much easier to burn off. mobil 1 is the most overrated oil out there. good thing their 5W-40 is a group IV.

 

I would like a list of the group IV motor oils. I think this is one of the main questions along with price. For a group III oil most syn. oils will work instead of paying a premium for Mobile 1 non group IV.

 

Choco, the idea that 5w is always greater viscosity than 0w is a myth. The idea that M1 is thin is CLEARLY hammered by the viscosity chart showing that there are much thinner oils of any given weight. And, though M1 does seem to have a propensity for slightly higher iron numbers and usage, it does still produce good wear numbers overall, keeps engines clean, and has a good formulation.

We can all diss ExxonMobil for being such a bunch of buttheads about not fessing up to not using the same amounts of real synthetics as they used to and still charging more for their oil, but it does work well in IC engines. I think the biggest modifier to the oil equation is simply that all the other oils have gotten better and M1 doesn't stand out as much as it used to.

But your generalizations are not as correct as you suspect.

 

yes, there are thinner oils than mobil 1 out there. there is always a car out there faster than yours, too. there is always someone better looking. always someone smarter. etc...

mobil 1 is still thin. compare mobil 1 to conventional oils. it's on the thin side.

i'm not saying mobil 1 is a bad oil. i'm saying GC is better. it's been proven time and time again. my "generalizations" are pretty darn accurate.

 

Ive been thinking of switching for a bit because my motor makes so much noise, but I think I might have a freak after reading all the comments about the M1 getting consumed so quick. I use the M1 5-30 synthetic and the same amount come out after 3500mi as I put in. I wont say it burns 0, but little enough that I could never tell. It is also barely even darkened up at that point, looks almost new when it comes out of the pan. Is this wierd?

 

Not weird..I have been using M1 5w30 synthetic or 10w30 since my 99 was new..I religiously change the oil at 3k..The car burns no oil & comes out clean as hell, My 98 is another story I am going to switch that to the 5w40 diesel stuff that was talked about in here. I will seafoam the car 1st..My 98 just runs really dirty, oil is black after 1500 miles

 

Then why keep repeating such an inaccurate generalization?


M1 5w-30 is 64.8/11.3. Mobil Clean 7500 5w-30 is 62.5/10.6. Which of those looks thicker to you?



I took a quick search through the UOAs at BITOG yesterday and took a look at the GC results. I'll have to look some more and crunch some numbers, but The LSx results I saw were nothing like magic. Patman's results are abby-normal, and should only be used as a target, not guaranteed.


Looks a little like "I reject your reality and substitute my own..."

 

I can understand not wanting to pay WS6 store for the oil...but if you think how much time and gas people waste driving around looking for GC...its not all that bad. Just click order and be done with the hassle.

 

Or just buy a different oil.

For people that keep up with a good maintenance schedule and change the oil regularly, they will truthfully see little to no difference in the performance of their engine over the years they own it using something like GC vs a M1 product.

Hell, I've seen GM V8 motors with nearly 300k on them with nothing but conventional Valvoline oil used since new.

It's great to try and use the oils that show the best results in a given engine, but really it's not worth going that far out of your way to do it, IMO. Unless you have that sort of time to kill.

 

dude no offense..but there is no excuse for having your low oil light come on. The low oil light is for people who know nothing about cars. There's really no excuse for going 4000 miles and not checking your oil..especially when your using a new oil for the first time and your not sure if your motor may consume this at a quicker rate than the oil you were previously using. I think i would me more concerned with running my motor that low on oil, than worried about which synthetic is thicker than the other. Thats just my opinion though..i dont mean for this to sound like i'm hatin on ya or anything..its just seems weird to be that worried about what oil you put in your car..but than you let it get low enough for the low oil light to come on..

 

Doesn't that light come on when you are about 2 quarts low? I have never seen a light..Out of curiosity I watched my oil pressure today on my 98..At idle it was at 42, driving, it was about 58..Not bad for that thin M1 5w30

 

what are you talking about? mobil 1 IS generally a very thin oil.

look at it like this: say you're 300 lbs. say one of your buddy's is 400 lbs. well, you're obviously a lot smaller than your buddy, but you're still a big fat guy. just because there's people out there fatter than you doesn't mean you're not fat yourself.

mobil 1 IS thin oil. it doesn't matter that other oils are thinner. it's thin and that's why LS1's tend to gobble it up.


they both are thin. one just happens to be even thinner than the other. either way, it's unappealing.


there's no such thing about magic. all that matters is that:

1.) they are better with GC
2.) the LS1 consumes less GC on average
3.) the GC lessens engine tick a little better
4.) the GC gives better oil pressure


you took my whole post out of context and made broad, sweeping generalizations that didn't encompass what i said. it didn't do much to my argument at all.