5W30 vs 5W40 in a GM car

[clarkz71]

Originally Posted By: Quattro Pete

My point was that the official MB 229.5 spec does not list any other grades apart from 0w-30, 5w-30, 0w-40, and 5w-40.



Correct again, and using a 229.5 oil only matters if you're in warranty.
Remember, I am a factory trained dealer tech. I know about MB oil approvals.

The only reason I posted the chart was to show MB, as well as some other manufacturers
do not restrict owners to a single operating temp oil weight like GM with 30 weight.

I'm using, as this thread is about, Motul 8100 X-Cess 5W40 which happens to be 229.5
not that it matters as I'm using it in a Northstar.

I have a large stock of it from my previous Mercedes 400E, which has a M119 4 cam V8
very much like the Northstar in many ways.

 

[clarkz71]

Originally Posted By: stchman
To the OP:

By running 5W-40 instead of 5W-30 do you think the engine will last longer? If the oil and filter are changed out at manufacturer's specified intervals, the engine will outlast the body.


Yes, in South Florida, the engine can/does get hot in traffic where most of my driving
is done. I don't trust a 30 weight in a 100K mile engine.

Originally Posted By: stchman

The only reason to run thicker oil in that car is if you take that car to the track for some really spirited driving.


That is a matter of opinion, you are in the minority if you read the whole thread.


Originally Posted By: stchman

GM knows that thicker oil protects engines better by virtue of the high performance Camaro and Corvette. Those engines spec a 5W-30 oil but GM specifies in the manual that if you are going to track race the car, they recommend running Mobil 1 15W-50.


I actually used Mobil 1 15W50 in my last Eldorado Northstar, a 1995 model
70,000 miles with it, ran great and got 28mpg on the highway

Originally Posted By: stchman

Morale of the story, run 5W-40 in your Caddy if you want, the engine won't last longer. You fuel economy might not be quite as good, but it might be insignificant. If you plan to take your Caddy to the track, run a thicker racing oil.


Well thank you for giving me permission to use the oil I like
But there will be no racing, so no need for a racing oil.

 

[stchman]

Originally Posted By: clarkz71
Originally Posted By: stchman
To the OP:

By running 5W-40 instead of 5W-30 do you think the engine will last longer? If the oil and filter are changed out at manufacturer's specified intervals, the engine will outlast the body.


Yes, in South Florida, the engine can/does get hot in traffic where most of my driving
is done. I don't trust a 30 weight in a 100K mile engine.

Originally Posted By: stchman

The only reason to run thicker oil in that car is if you take that car to the track for some really spirited driving.


That is a matter of opinion, you are in the minority if you read the whole thread.


Originally Posted By: stchman

GM knows that thicker oil protects engines better by virtue of the high performance Camaro and Corvette. Those engines spec a 5W-30 oil but GM specifies in the manual that if you are going to track race the car, they recommend running Mobil 1 15W-50.


I actually used Mobil 1 15W50 in my last Eldorado Northstar, a 1995 model
70,000 miles with it, ran great and got 28mpg on the highway

Originally Posted By: stchman

Morale of the story, run 5W-40 in your Caddy if you want, the engine won't last longer. You fuel economy might not be quite as good, but it might be insignificant. If you plan to take your Caddy to the track, run a thicker racing oil.


Well thank you for giving me permission to use the oil I like
But there will be no racing, so no need for a racing oil.


By running 5W-40 instead of 5W-30, do you have any quantifiable data that the engine in your Eldorado is going to last longer? Is it just a "it makes me feel better" thing?

The manufacturer in the manual states 5W-30, not "5W-30 unless you live in southern Florida, then use 5W-40".

You don't "trust" 5W-30, there is probably millions of miles of research on hundreds of vehicles that say 5W-30 is a viscosity you can trust.

It is not that I "gave" you permission, you came on here asking questions, I tried to answer your questions but you dismiss the answer as it does not agree with your sensibilities. Your mind was made up LONG before you asked the question.

Since you are not going to race the Caddy, 5W-30 or 5W-40 will both protect the engine well.

 

[ExMachina]

Originally Posted By: stchman
Since you are not going to race the Caddy, 5W-30 or 5W-40 will both protect the engine well.


What viscosity to use is indeed a judgement call, as many have pointed out above.
Racing heats up the oil more (reducing its running viscosity) under sustained high-torque loads and thats why higher viscosity grades are often recommended, because in racing we expect oil thinning (extra heat), maybe some fuel dilution along the way, and high loads.
The REAL goal is Oil Film Thickness (OFT), and we are guessing at "How Much OFT Is Enough".

Its true higher viscosity oil results in less cam lobe wear, since those surfaces always have at least some very thin to even zero OFT, and the more viscosity, the less Boundary Lubrication (BL), which means zero or near-zero OFT. In a similar way, upper and lower ends of the cylinder wall experience BL at times which should be minimized by using a thicker oil. As you thin an oil excessively, risk increases for a spun journal bearing.

I like what bobbydavro, a bitog Castrol person, said one time. He mentioned that 0w-20 and 5w-20 oils have difficulty passing RNT cam wear tests (like GM's GMPTE-T DUR021 or VW's radionuclide cam/tappet wear test). This is because more BL or mixed-BL conditions occur as you drop down in viscosity.

 

[donnyj08]

Originally Posted By: clarkz71
Originally Posted By: Quattro Pete

My point was that the official MB 229.5 spec does not list any other grades apart from 0w-30, 5w-30, 0w-40, and 5w-40.



Correct again, and using a 229.5 oil only matters if you're in warranty.
Remember, I am a factory trained dealer tech. I know about MB oil approvals.

The only reason I posted the chart was to show MB, as well as some other manufacturers
do not restrict owners to a single operating temp oil weight like GM with 30 weight.

I'm using, as this thread is about, Motul 8100 X-Cess 5W40 which happens to be 229.5
not that it matters as I'm using it in a Northstar.

I have a large stock of it from my previous Mercedes 400E, which has a M119 4 cam V8
very much like the Northstar in many ways.


It sounds like you already made your mind up before you asked on this forum. GM engines wear well and last a long time on 30wt oils. I would wager the newer LS engines will outlast almost anything from MB aside from the old Diesel engines.

If you want to run a 40wt oil you will be perfectly fine to do so. Many in the LS community run M1 0w40 which meets MB specs and have great success.

The point most here are trying to make is that in a GM engine a good 30wt is and excellent choice.

There is nothing wrong with thicker oil, However I believe that one should pick an oil that is thin enough to provide good protection and cooling, without causing viscous drag.

We've seen a few of the previous generation 5.3L V8's ran on 5w20 and return excellent wear number in UOA's.

we see a lot of vehicles on the road today with 200K+ miles on "thin" 20wt's. Many of those engines still do not use oil and are clean and responsive. Don't fear thin oil!!

I personally would just run M1 0w40 in your Northstar and call it a day.

 

[zeng]

Originally Posted By: ExMachina
Originally Posted By: stchman
Since you are not going to race the Caddy, 5W-30 or 5W-40 will both protect the engine well.


What viscosity to use is indeed a judgement call, as many have pointed out above.
Racing heats up the oil more (reducing its running viscosity) under sustained high-torque loads and thats why higher viscosity grades are often recommended, because in racing we expect oil thinning (extra heat), maybe some fuel dilution along the way, and high loads.
The REAL goal is Oil Film Thickness (OFT), and we are guessing at "How Much OFT Is Enough".

Its true higher viscosity oil results in less cam lobe wear, since those surfaces always have at least some very thin to even zero OFT, and the more viscosity, the less Boundary Lubrication (BL), which means zero or near-zero OFT. In a similar way, upper and lower ends of the cylinder wall experience BL at times which should be minimized by using a thicker oil. As you thin an oil excessively, risk increases for a spun journal bearing.

I like what bobbydavro, a bitog Castrol person, said one time. He mentioned that 0w-20 and 5w-20 oils have difficulty passing RNT cam wear tests (like GM's GMPTE-T DUR021 or VW's radionuclide cam/tappet wear test). This is because more BL or mixed-BL conditions occur as you drop down in viscosity.




Quote:
Yes, in South Florida, the engine can/does get hot in traffic where most of my driving
is done. I don't trust a 30 weight in a 100K mile engine.




I believe Oil Film Thickness is proportional to operating oil viscosity.

Thus under identical operating conditions , xW40 would offer OP higher OFT than xW30. This

should translate into higher margin of safety in terms of engine wear protection , considering

OP's operating requirements.

 

[Garak]

Originally Posted By: clarkz71
The only reason I posted the chart was to show MB, as well as some other manufacturers do not restrict owners to a single operating temp oil weight like GM with 30 weight.

GM currently uses more than just 5w-30. Their biggest beef with 40 grades historically has been poor 10w-40 examples available back in the day. They really insisted on a 10w-30 back then. Of course, they had no problems with using 15w-40 as their diesels began to roll onto the scene.

For your 2000 Eldorado, a 5w-40 or 0w-40 would work fine. You'll also find that 5w-30 (and 10w-30) has served GM fine for many, many years.

 

[zeng]

Originally Posted By: Garak
Originally Posted By: clarkz71
The only reason I posted the chart was to show MB, as well as some other manufacturers do not restrict owners to a single operating temp oil weight like GM with 30 weight.

GM currently uses more than just 5w-30. Their biggest beef with 40 grades historically has been poor 10w-40 examples available back in the day. They really insisted on a 10w-30 back then. Of course, they had no problems with using 15w-40 as their diesels began to roll onto the scene.

For your 2000 Eldorado, a 5w-40 or 0w-40 would work fine. You'll also find that 5w-30 (and 10w-30) has served GM fine for many, many years.


Just curious why would GM's having issues with 10W-40 in those days?

Care to elaborate enlighten please .......

 

[Falcon_LS]

My LL8, although a totally different animal, was spec'd for 5W-30 meeting GM 6094M in the USDM. Export calls for anything from 0W-30 to 20W-50 meeting ACEA A3 - doubt there'll be any problems running 5W-40 in a NS.

 

[Garak]

Originally Posted By: zeng
Just curious why would GM's having issues with 10W-40 in those days?

I don't know if it was the viscosity index improvers or what, but there were concerns with sludging. So, GM warned against the use of the viscosity. If I come across any of the old manuals at home someday, I'll post the wording.

 

[zeng]

Originally Posted By: clarkz71
Originally Posted By: zeng


Hmm ...... care to elaborate typical Mercedes clearance range for say,a 2 inch main/rod journal ?




Connecting rod bearing clearance on a M119 V8 of the same period (1990-1999)
as the Nortstar is .0017 to .0021 with a service limit of .0031


With conrod bearing diameter of 48 mm, its specific clearance range is 0.896 to 1.104

thousandths per inch. Limit 1.646 thousandths per inch.

clarkz71 , are all other European and US bearing clearances this coarse ?? Just curious ......

Your bearing clearance is very much on the coarse side as compared to an early 1990's Japanese

Mitsubishi 4G15 4I engine 48 mm main bearing diameter of clearances range of 0.00079 inch

-0.00158 inch.Service limit 0.004 inch. Its recommended oil is 10W30 to 20W50

depending on ambients.

It appears to me your Northstar/Mercedes M119 bearing clearances are on the coarse side and

would be more compatible with xxW40 or xxW50 , rather than a xxW30.

Just my 2 cents.

 

[zeng]

Originally Posted By: Garak
Originally Posted By: zeng
Just curious why would GM's having issues with 10W-40 in those days?

I don't know if it was the viscosity index improvers or what, but there were concerns with sludging. So, GM warned against the use of the viscosity. If I come across any of the old manuals at home someday, I'll post the wording.


Would really appreciate any updates , for it shouldn't be viscosity-related I believe .

 

[Garak]

It definitely wasn't the viscosity itself (as in it being a 40), I'm certain. I haven't happened across any manuals, but I must have at least one laying around somewhere. It was a warning specifically against the 10w-40 grade, not 15w-40, and not the usual, current warning about using anything else except whatever they want you to use all the time.

 

[Shannow]

Originally Posted By: Garak
Originally Posted By: zeng
Just curious why would GM's having issues with 10W-40 in those days?

I don't know if it was the viscosity index improvers or what, but there were concerns with sludging. So, GM warned against the use of the viscosity. If I come across any of the old manuals at home someday, I'll post the wording.


When at Uni, I had access to the SAE microfiche, and there were a couple of articles on that grade sludging up and turning solid on high speed desert runs.

Only thing that I can find with a brief look is Pop Science article.

Popular Mechanics

It's still my least favourite grade.

 

[Garak]

Thanks for those. The dates on those links definitely coincides with my memory of the issue in the taxi fleet maintenance days. Also, PS and PM were useful, then.

 

[zeng]

Originally Posted By: Shannow
Originally Posted By: Garak
Originally Posted By: zeng
Just curious why would GM's having issues with 10W-40 in those days?

I don't know if it was the viscosity index improvers or what, but there were concerns with sludging. So, GM warned against the use of the viscosity. If I come across any of the old manuals at home someday, I'll post the wording.


When at Uni, I had access to the SAE microfiche, and there were a couple of articles on that grade sludging up and turning solid on high speed desert runs.

Only thing that I can find with a brief look is Pop Science article.

Popular Mechanics

It's still my least favourite grade.



Thanks Shannow , for the enlightening articles and leads about GM's take on a certain VII

polymer type (of certain concentration weight) in 10W40 developing carbon deposits that could

result in engine-threatening preignition issues in early 80's .

 

[Merkava_4]

I bought a bottle of Valvoline Synpower 5W-40 one time just for kicks. It was the middle of summer here in California and that 5W-40 looked quite a bit thinner than the other bottles of 10W-30 going down the funnel. It was definitely NOT what I'd call a thick oil. Maybe those HDEO 5W-40's are thicker; I don't know.

 

[Garak]

It doesn't matter what it looks like, Merk.

You've got a KV100 range for the 40 part, and a CCS and MRV for the 5w-XX or 10w-XX part, and then an HTHS. The 5w-40 is going to be decidedly thicker at operating temperatures than the ILSAC 10w-30. If you're concerned about room temperature viscosity, you should try a monograde for kicks!

 

[userfriendly]

The only thing that will shear a mono-grade is Saskatchewan Highway 13.

 

[clarkz71]

Originally Posted By: zeng


I believe Oil Film Thickness is proportional to operating oil viscosity.

Thus under identical operating conditions , xW40 would offer OP higher OFT than xW30.

This should translate into higher margin of safety in terms of engine wear protection ,
considering the OP's operating requirements.

Bingo, that's what my opinion is.

I have to thank all the members that contributed to this thread.

Some very impressive knowledge on oil here.