5W30 vs 5W40 in a GM car

[clarkz71]

As a 30 Mercedes veteran technician, I find it strange that GM insists on a 30 weight oil, whether a 5W30 or 10W30. These are the only oils recommended in the manual. Where Mercedes, with bearing clearances just as tight allows a full range of viscosities of oil ranging from 0W30 to 20W50 based on climate/operating temperature My question is based on a recent thread on a Cadillac forum where I asked if anyone knew why GM insists on a 30 weight and why a 5W40 would not be as good or better. Of course, they all drink the GM koolaid and say using anything other then the recommended oil will result in severe engine damage. So, for my 2000 Eldorado with the Northstar engine, 5W30 vs 5W40 full synthetic. I use Motul 8100 X-cess which is a group IV oil. From the sticky "what is the best oil" 1. What kind of vehicle you have 2000 Eldorado 2. What your owner's manual says -- not just viscosity, but certifications (look for acronyms like API SM, ILSAC GF-4, etc.) and change intervals as well Owners manual calls for a 5W30 "starburst" approved oil, no API recommendation 3. Where you live South Florida 4. How you drive (easy? hard? fast? slow?) Mix of these 5. What your daily drive is like (short trips? long trips? city? highway?) All local driving in 50% stop & go, sitting at lights. Engine temps 203° to 225°f 6. Whether your car has any known problems None, engine is in excellent condition, 111,500 miles

 

[Phishin]

You and I both know, that running any HDEO in that car would be fine. Any 5w40 would be a great choice in that Northstar. Any 10w40 would be just fine as well. Since you in Florida, you could get away with a 20w50, but if you aren't consuming any oil, I see no reason to step up this high. My biggest concern would be the head bolts......your N* hasn't blown a head gasket yet??

 

[clarkz71]

Originally Posted By: Phishin

My biggest concern would be the head bolts......your N* hasn't blown a head gasket yet??

No, those are hit and miss. GM did change the block casting and used longer head bolts in the 2000 model year. 96-99 were the worst years for HG failures. And yes, I know the 5W40 Motul is fine for my engine, just wanted to come on here where the "true experts" on oil are to verify my belief. I tried to get an answer on the Cadillac forum from an engineering stand point. I should have known better.

 

[toyota62]

Motul X-cess is a group3 base oil. Few years back I used it in my old Camry. I asked Motul and they said its group3 base. Then again this was 10 plus years ago. They may have changed the formula but highly unlikely

 

[bigt61]

I used 15W-50 M1 (leftover from race car) in my '99 Aurora with the 4.0L Northstar V8. No issues whatsoever, but I wasn't doing any below 0F starts. Northstars tend to run hot and are hard on oil, so it may have even been a plus. IMO, these engines really need synthetic of some sort. 240F water was common on a hot day in traffic.

 

[clarkz71]

Originally Posted By: toyota62

Motul X-cess is a group3 base oil. Few years back I used it in my old Camry. I asked Motul and they said its group3 base. Then again this was 10 plus years ago. They may have changed the formula but highly unlikely

That is possible, I based my information on the fact that this version 5W40 is both MB 229.3 and 229.5 approved and in Germany only true synthetics (IV/V) can be sold as being synthetic In any case the specs are very good.

 

[SR5]

Originally Posted By: Phishin

Any 5w40 would be a great choice in that Northstar. Any 10w40 would be just fine as well. Since you in Florida, you could get away with a 20w50, but if you aren't consuming any oil, I see no reason to step up this high.

+ 1 Or a 0W40 Euro / EP synthetic. However that Motul 5W40 synthetic sounds great. I liked how in the old days they gave you a range of viscosities based on climate. Now it's more of a one size fits all oil, which is dumbing it down. Still atleast GM says 5W30, which to me is a better default oil weight than 5W20.

 

[clarkz71]

Originally Posted By: SR5

I liked how in the old days they gave you a range of viscosities based on climate. Now it's more of a one size fits all oil, which is dumbing it down. Still atleast GM says 5W30, which to me is a better default oil weight than 5W20.

Mercedes still does the viscosity chart, here's a recent one..........

 

[clarkz71]

Got to love google, some searching and I found this Motul's 8100 X-Cess, In Detail Motul's 8100 oil begins as synthetic ester base stocks, and then has polyalphaolefin (a Group IV oil) blended in, along with proprietary additives. The combination of these means that Motul's 8100 oils maintain their viscosity and have very low shearing over time, and provide superior protection against wear and corrosion. Motul's 8100 X-Cess oils are their strongest, most resilient oils in the 8100 lineup. Unlike the Eco-nergy series, which use long thin chained molecules to provide resistence-free lubrication and improve gas mileage, X-Cess's composition is designed to resist impact and compression while still targeting low friction characteristics. In short, although Eco-nergy frees up some power by providing the least resistence to rotation within the engine, X-Cess protects engines that deal with large amounts of torque and forces applied to bearings and cylinder walls at the cost of a few horsepower. We think that X-Cess is definitely the right choice to make for high power applications. And this from another thread on here to confirm........

Originally Posted By: a4tdi

Motul Group III oils are labeled as "Technosynthese". Their fully-synthetic oils are labeled as "100% synthetic" or simply "Synthetic".Products like E-tech 0w40 are ester-based, hence the "E" in E-tech. I believe that 8100 X-cess is a PAO/ester blend, but I may be incorrect on that. I'm sure the real Motul experts will chime in if I'm wrong.

 

[zeng]

Originally Posted By: clarkz71

As a 30 Mercedes veteran technician, I find it strange that GM insists on a 30 weight oil, whether a 5W30 or 10W30. These are the only oils recommended in the manual. Where Mercedes, with bearing clearances just as tight allows a full range of viscosities of oil ranging from 0W30 to 20W50 based on climate/operating temperature

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

Originally Posted By: clarkz71

My question is based on a recent thread on a Cadillac forum where I asked if anyone knew why GM insists on a 30 weight and why a 5W40 would not be as good or better. Of course, they all drink the GM koolaid and say using anything other then the recommended oil will result in severe engine damage. So, for my 2000 Eldorado with the Northstar engine, 5W30 vs 5W40 full synthetic. I use Motul 8100 X-cess which is a group IV oil. Owners manual calls for a 5W30 "starburst" approved oil, no API recommendation

Looks like xW40 which offers better wear protection is the consensus , against GM's recommended xW30.

 

[KCJeep]

If you want to run that 5w40 by all means do so it won't hurt a thing. I wish there were a better selection of PCMO 5w40's available at good pricing, but then again that is exactly why M1 0w40 is one of the darlings here. GM most likely went with 30 grades for economy and lack of availability of 5w40's back then, plus the fact they aren't too worried about their cars being run on the Autobahn. JMO.

 

[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

 

[clarkz71]

Originally Posted By: KCJeep

If you want to run that 5w40 by all means do so it won't hurt a thing. I wish there were a better selection of PCMO 5w40's available at good pricing, but then again that is exactly why M1 0w40 is one of the darlings here.

Mobil 1 0W40 is factory fill for MB and is used by the dealers.

Originally Posted By: KCJeep

GM most likely went with 30 grades for economy and lack of availability of 5w40's back then, plus the fact they aren't too worried about their cars being run on the Autobahn. JMO.

100% correct, hence the "Starburst" energy efficient [censored]. CAFE and the EPA

 

[TFB1]

This is nothing more than the 5/10W-30 was used for CAFE numbers game, going to a 40 weight will decrease mileage maybe .2 MPG(in FL possibly not at all)...

 

[Quattro Pete]

Originally Posted By: clarkz71

Mercedes still does the viscosity chart, here's a recent one..........

Although, they also require that an oil meets the 229.5 spec (for gasoline engines), which limits the viscosity grades that you can use. You won't find any Xw-50 or Xw-60, or 10w-XX, or 15w-XX, or 20W-XX oils on the 229.5 list.

 

[clarkz71]

Originally Posted By: Quattro Pete

Although, they also require that an oil meets the 229.5 spec (for gasoline engines), which limits the viscosity grades that you can use. You won't find any Xw-50 or Xw-60, or 10w-XX, or 15w-XX, or 20W-XX oils on the 229.5 list.

5W50 Mobil 1 MB 229.3 is used in the New SLR and SLS AMG cars. As a 229.3 it can be used in all MB cars made before the 229.5 spec. There are no xW60 weight oils on that chart. I'll post the MB chart from the Factory manual

 

[Quattro Pete]

Quote:

5W50 Mobil 1 MB 229.3 is used in the New SLR and SLS AMG cars.

Is that the M159 engine in the new SLS AMG? If so, it calls for 229.5 spec oil, and only 0w-40 and 5w-40 grades are allowed. The M155 engine in the SLR is in fact back specced to 229.3.

Quote:

As a 229.3 it can be used in all MB cars made before the 229.5 spec.

Sure, but 229.3 is an old spec. I should have clarified that I was referring to all current production gasoline engines. Apparently exotics such as the SLR are exempted.

Quote:

There are no xW60 weight oils on that chart.

I see 10w-60 on it.

 

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

 

[clarkz71]

Originally Posted By: Quattro Pete

Sure, but 229.3 is an old spec. I should have clarified that I was referring to all current production gasoline engines. Apparently exotics such as the SLR are exempted.

Correct, even though they are current cars, they use the 229.3 5W50

Originally Posted By: Quattro Pete

I see 10w-60 on it.

Correct, I was looking at the 5W oils That is a Mercedes owners manual chart, which means somewhere in Europe there are MB approved oils in those weights. 10W60 is a 229.1 oil, I can research what model(s) used it but why. This is the current chart in WIS, MB dealer Work Information System These oil must be available somewhere or they wouldn't be on there. This is the factory manual MB uses online

 

[Quattro Pete]

Originally Posted By: clarkz71

That is a Mercedes owners manual chart, which means somewhere in Europe there are MB approved oils in those weights.

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. http://bevo.mercedes-benz.com/bevolisten...ent_action=show The other grades listed on the chart you posted most likely only apply to very very old MB engines designed for 229.1 spec or older.