[RallyRunner]

Originally Posted by SS_Don

In the referenced Dexos R list there are four 0W-40 listed. What is the difference between those four oils?

i'm not an expert by any means, but to break it down in a basic way;

0W-40 FS is a great overall oil. strong detergent package, resists oxidation well, but shears down to a high 30 weight oil faster. it is the easiest and cheapest to find. this was the factory fill in 911 Cup cars for a while.

0W-40 Supercar is slightly thicker and track capable. It will run out of detergency faster than FS in exchange for the ability to endure a bit more abuse and still stay within grade.

0W-40 X4 is going to be the most shear-stable, track capable 40 weight in this list and starts off the thickest viscosity of the 3. like Supercar it has less detergency than FS.

this is a great video by Lake Speed (a tribologist) who can break it down a bit although its just a short look at a complicated subject.
https://youtu.be/LUr4iTjXbhg?feature=shared&t=695

the good news is; they're all great oils. hard to go wrong. personally i would not bother at all with M1's 5W-40, its specs are unimpressive and Mobil looks to place the most R&D and engineering horsepower behind the 0W-40 line.

[SS_Don]

Originally Posted by RallyRunner

i'm not an expert by any means, but to break it down in a basic way;

0W-40 FS is a great overall oil. strong detergent package, resists oxidation well, but shears down to a high 30 weight oil faster. it is the easiest and cheapest to find. this was the factory fill in 911 Cup cars for a while.

0W-40 Supercar is slightly thicker and track capable. It will run out of detergency faster than FS in exchange for the ability to endure a bit more abuse and still stay within grade.

0W-40 X4 is going to be the most shear-stable, track capable 40 weight in this list and starts off the thickest viscosity of the 3. like Supercar it has less detergency than FS.

this is a great video by Lake Speed (a tribologist) who can break it down a bit although its just a short look at a complicated subject.
https://youtu.be/LUr4iTjXbhg?feature=shared&t=695

the good news is; they're all great oils. hard to go wrong. personally i would not bother at all with M1's 5W-40, its specs are unimpressive and Mobil looks to place the most R&D and engineering horsepower behind the 0W-40 line.

Thanks for the explanation.


Sent from my iPhone using Tapatalk

[Msquared]

The "old" M1 0w-40 FS is new now: reformulated with half other calcium and a different kind of base stock. It now has an API rating of SP. THAT'S how it got the Dexos R rating. It's not that the old formula met the specs all along: it didn't, especially for use in direct-injection engines. If you've been using the $25 Walmart jugs for constant use, you have been using the wrong oil. My guess is that the old inventory will take a while to disappear, and that the new SP-rated stuff will no longer be cheap. If someone finds the new, SP-rate FS "European" oil for cheap, let us know!

I have always used the x3 in my 2020 because it only called for Dexos 2, so the x3 met that spec, and the x3 doesn't shear down as easily in hard use. Because I autocross and track my car, it made sense to trade off some time/mileage duration of the oil for the improved shear resistance. This is the stuff that Autozone has been selling. Now my car is out of warranty and it just stopped being my daily driver this year. Therefore, I'm about to switch to Supercar 5w-50 because the cold-start flow capability of a 0w is no longer very important to me, but the extra film strength and HTHS might be useful, especially on track days.

[RallyRunner]

Originally Posted by Msquared

The "old" M1 0w-40 FS is new now: reformulated with half other calcium and a different kind of base stock. It now has an API rating of SP.

this is an excellent point. the older SN rated oil was high calcium (bad for Low Speed Pre Ignition...not an issue in our cars, but still) and had a lower starting viscosity of around 12.8 centistokes, barely above a 40 weight (30wt cutoff is 12.6). the new SP formula is low calc and starts out at 13.6 cst. High Temp High Shear rating remains approx the same at 3.6, with the baseline for that rating coming at 3.5.

my local wally world here in E. GA shows FS SP-formula on rollback for under $25/jug.
https://www.walmart.com/ip/Mobil-1-F...0&from=/search

[m6-lt1]

Got a question for you oil experts. I want to switch to 5w-50 but I do occasionally drive my car in the winter. Would turning the car on in 20 degree weather be bad if I have 5w-50? These engines originally came with a 5w oil in it when they came out in 2014. Because they were factory filled with 5w-30 I feel like 5w-50 can be used in the winter. I think they switched to 0w-40 instead of 5w-40 mainly due to availability. These engines haven’t changed since their introduction in 2014 in the C7 aside from crappy quality control on the post covid engines.

[Gunkk]

Originally Posted by m6-lt1

Got a question for you oil experts. I want to switch to 5w-50 but I do occasionally drive my car in the winter. Would turning the car on in 20 degree weather be bad if I have 5w-50? These engines originally came with a 5w oil in it when they came out in 2014. Because they were factory filled with 5w-30 I feel like 5w-50 can be used in the winter. I think they switched to 0w-40 instead of 5w-40 mainly due to availability. These engines haven’t changed since their introduction in 2014 in the C7 aside from crappy quality control on the piston covid engines.

The low-temp viscosity varies more or less proportionally to the high-temp viscosity. Just because both are 5w doesn't mean they're the same at low temp. Data from Mobil1's site: kinematic viscosity is 104.3 for the 5w50 vs 64 for the 5w30 (both at 40C ASTM D445).

Stick with 5w30 in winter.

[m6-lt1]

Originally Posted by Gunkk

The low-temp viscosity varies more or less proportionally to the high-temp viscosity. Just because both are 5w doesn't mean they're the same at low temp. Data from Mobil1's site: kinematic viscosity is 104.3 for the 5w50 vs 64 for the 5w30 (both at 40C ASTM D445).

Stick with 5w30 in winter.

Thank you. So I wouldn’t ever use 5w-30 because you can’t track on that. You can track either on 0w-40 or 5w-50. I want to switch to the 5w-50 for extra protection on track but wanted to know if I can leave it in once winter hits instead of doing an oil change back to 0w-40. Car wouldn’t drive in anything below 20.

[Msquared]

Originally Posted by m6-lt1

Thank you. So I wouldn’t ever use 5w-30 because you can’t track on that. You can track either on 0w-40 or 5w-50. I want to switch to the 5w-50 for extra protection on track but wanted to know if I can leave it in once winter hits instead of doing an oil change back to 0w-40. Car wouldn’t drive in anything below 20.

Gunkk makes a good point. And remember, 40C is still around 96F if memory serves. It's a cold start on a very hot summer day. 20F will probably exaggerate that cold-start viscosity difference even more.

I always stuck with 0w-40 x3 because until this year I daily-drove it year-round, yet it provides a lot more resistance to shearing down in viscosity with hard use than the Supercar 0w-40. The X4 is probably pretty similar, and it's 40C KV is 72: still flowing much better than 5w-50 Supercar. I'm willing to try 5w-50 because the car won't be cold-started much at all anymore (probably 5% as often as before) in any temp. That oil's pour point still goes down to -48C, so it will still flow in any weather I'll ever drive the car in...just not as fast. My track day mileage is going up even as my cold-start rate has plummeted, so in my case I think this tradeoff makes sense. However, the X3 (and probably the X4?) still make a great case as the best jack-of-all trades oil for a tracked LT1 that also sees plenty of street use.

[SnakeEyeSS]

Originally Posted by Msquared

The "old" M1 0w-40 FS is new now: reformulated with half other calcium and a different kind of base stock. It now has an API rating of SP. THAT'S how it got the Dexos R rating.

Nope, it now has a rating of SQ.
https://www.mobil.com/en-pl/passenge...bil-1-fs-0w-40


And this seems to predate the Dexos R approval(considering the webpage only lists SQ), so I suggest people check some bottles in their area. I will be next time I'm in the store.

[2SS Capt]

Originally Posted by Msquared

40C is still around 96F if memory serves. It's a cold start on a very hot summer day.

Actually, 40°C is 104°F...

50°C = 122°F
45°C = 113°F
40°C = 104°F
35°C = 95°F
30°C = 86°F
25°C = 77 °F
20°C = 68°F
15°C = 59°F
10°C = 50°F
5°C = 41°F
0°C = 32°F

Every 5°C = 9°F

[Msquared]

Originally Posted by SnakeEyeSS

Nope, it now has a rating of SQ.
https://www.mobil.com/en-pl/passenge...bil-1-fs-0w-40

Interesting. That spec page is significantly different than the ones Lake Speed compared in the video linked above, including the 100C kinematic viscosity. The bottle he has in the video shows SP, and that video is only 4 months old.

Originally Posted by 2SS Capt

40°C = 104°F

Thanks for that. I shouldn't have been so lazy to not just look it up.

[SnakeEyeSS]

Originally Posted by Msquared

Interesting. That spec page is significantly different than the ones Lake Speed compared in the video linked above, including the 100C kinematic viscosity. The bottle he has in the video shows SP, and that video is only 4 months old.


Thanks for that. I shouldn't have been so lazy to not just look it up.

Is it just me, or does it kind of seem like Mobil 1 knew what was coming with the trucks?

[SnakeEyeSS]

Originally Posted by Msquared

Interesting. That spec page is significantly different than the ones Lake Speed compared in the video linked above, including the 100C kinematic viscosity. The bottle he has in the video shows SP, and that video is only 4 months old.


Thanks for that. I shouldn't have been so lazy to not just look it up.

I just notice my link is for Poland. The US site still lists SP.

[DamonZ28]

Originally Posted by cdrptrks

Bumping this old thread again...still available with the new ESP X4 formula if you click on "$35.99 Mobil 1 Bundle" (https://www.autozone.com/motor-oil-a...rt/1177215_0_0) that was recently DexosR certified: https://www.gmdexos.com/brands/dexosr/index.html

$72 + tax for 10 quarts of warranty approved oil and you might be able to return the 2 oil filters to get some money back but that isn't guaranteed.

There's always an expiration date listed for the deal but AutoZone has been perpetually renewing it for years as far as I can tell.

I just looked this up. The price is now at $29.99 per 5, but the oil filter is up to $7.59 each now (for the STP). For over $15, you'd definitely want to return them. That brings the total to $80 + tax (before any returns).