Incoming oil thread
Thread Starter
Melting Slicks
Joined: Nov 2011
Posts: 3,183
Likes: 265
From: Virginia
Incoming oil thread
The “ which oil is the best” debate has been beat to death and I know any big name brand synthetic oil will be fine so I’m not trying to start a debate, but I did have a quick question for you oil gurus.
I’ve always heard people talk about how thin and watery Mobil1 5w30 is but I had some time to kill earlier and was looking up some specs on a few different oils and I’m seeing some data that doesn’t add up. All are 5w30 oils:
Mobil1 11.0 cst @ 100°
Amsoil signature series 10.3 cst @ 100°
Pennzoil Ultra Platinum 9.8 cst @ 100°
so the reason I’m even looking this up is because I did want to run just a little bit thicker oil on my car since the miles are starting to get up there and it gets pretty hot here in the summer. I realize I could just use Mobil1 0w40 and be fine but my car doesn’t see any track time so I don’t know that’s the best option for me.
So these numbers I posted I noticed are at 100°, could it be that at full operating temperature that pattern isn’t consistent and maybe the Mobil1 thins out more than the other two compared?
again I know I will be perfectly fine with anyone of those three oils and I may just flip a coin on which one I’m going to use but does anyone know a little bit more on this? Just curious
I’ve always heard people talk about how thin and watery Mobil1 5w30 is but I had some time to kill earlier and was looking up some specs on a few different oils and I’m seeing some data that doesn’t add up. All are 5w30 oils:
Mobil1 11.0 cst @ 100°
Amsoil signature series 10.3 cst @ 100°
Pennzoil Ultra Platinum 9.8 cst @ 100°
so the reason I’m even looking this up is because I did want to run just a little bit thicker oil on my car since the miles are starting to get up there and it gets pretty hot here in the summer. I realize I could just use Mobil1 0w40 and be fine but my car doesn’t see any track time so I don’t know that’s the best option for me.
So these numbers I posted I noticed are at 100°, could it be that at full operating temperature that pattern isn’t consistent and maybe the Mobil1 thins out more than the other two compared?
again I know I will be perfectly fine with anyone of those three oils and I may just flip a coin on which one I’m going to use but does anyone know a little bit more on this? Just curious
Race Director
Joined: Jul 2005
Posts: 12,042
Likes: 3,583
From: Central MO
Take a look at oil test results for the three oils you are asking about in this blog:
https://540ratblog.wordpress.com/
Be warned there's a ton of information and it will take you a while to find the most current test results. The most recent blog results I looked at (late last year) for your mentioned oils would be ranked Amsoil Signature Series, Pennzoil Platinum, and Mobil 1.
I was a Pennzoil Platinum user since 2008 based on resistance to shearing, because I had a GM PV6 3.6L DOHC engine that sheared oil badly. I switched to Quaker State Full Synthetic in 2022 because of its very high engine wear resistance rating. As you stated, any of the mentioned oils are fine to use. I don't use the Amsoil because it is not API certified, it's only compliant, and it's not readily available everywhere. As for the other oils, I figure why not use an arguably better oil that costs the same as the others.
https://540ratblog.wordpress.com/
Be warned there's a ton of information and it will take you a while to find the most current test results. The most recent blog results I looked at (late last year) for your mentioned oils would be ranked Amsoil Signature Series, Pennzoil Platinum, and Mobil 1.
I was a Pennzoil Platinum user since 2008 based on resistance to shearing, because I had a GM PV6 3.6L DOHC engine that sheared oil badly. I switched to Quaker State Full Synthetic in 2022 because of its very high engine wear resistance rating. As you stated, any of the mentioned oils are fine to use. I don't use the Amsoil because it is not API certified, it's only compliant, and it's not readily available everywhere. As for the other oils, I figure why not use an arguably better oil that costs the same as the others.
Thread Starter
Melting Slicks
Joined: Nov 2011
Posts: 3,183
Likes: 265
From: Virginia
Take a look at oil test results for the three oils you are asking about in this blog:
https://540ratblog.wordpress.com/
Be warned there's a ton of information and it will take you a while to find the most current test results. The most recent blog results I looked at (late last year) for your mentioned oils would be ranked Amsoil Signature Series, Pennzoil Platinum, and Mobil 1.
I was a Pennzoil Platinum user since 2008 based on resistance to shearing, because I had a GM PV6 3.6L DOHC engine that sheared oil badly. I switched to Quaker State Full Synthetic in 2022 because of its very high engine wear resistance rating. As you stated, any of the mentioned oils are fine to use. I don't use the Amsoil because it is not API certified, it's only compliant, and it's not readily available everywhere. As for the other oils, I figure why not use an arguably better oil that costs the same as the others.
https://540ratblog.wordpress.com/
Be warned there's a ton of information and it will take you a while to find the most current test results. The most recent blog results I looked at (late last year) for your mentioned oils would be ranked Amsoil Signature Series, Pennzoil Platinum, and Mobil 1.
I was a Pennzoil Platinum user since 2008 based on resistance to shearing, because I had a GM PV6 3.6L DOHC engine that sheared oil badly. I switched to Quaker State Full Synthetic in 2022 because of its very high engine wear resistance rating. As you stated, any of the mentioned oils are fine to use. I don't use the Amsoil because it is not API certified, it's only compliant, and it's not readily available everywhere. As for the other oils, I figure why not use an arguably better oil that costs the same as the others.
Here’s the question though, I have Kooks high flow cats so with the high Zinc is it going to wreck my cats? I know a high zinc oil is hard on cats but does anyone know if the T6 5w40 formula is the same now as it has been for a long time? Maybe use it every other oil change?
Last edited by bwill03z; Mar 24, 2025 at 10:20 PM.
Le Mans Master
Joined: Dec 2013
Posts: 6,337
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From: Charles Town WV
2024 Corvette of the Year Finalist - Modified
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I'm sure I'll get flamed for this but I run Rotella 15w40 in every LS I've ever had...I probably lose a half of a horsepower for it but the **** works and I've never had one with a bad looking bearing when I took them apart. The guy that told me to start doing this has probably had more LS platform cars than anyone I know, everything from trucks to cars to ls swapped buggies. Took his word for it and its worked well for me every since.
Safety Car
Joined: May 2016
Posts: 4,662
Likes: 1,846
From: Erlanger, Kentucky
I would go with the Mobil 1 0W40 SuperCar. It's viscosity is higher than 5w30 at both 40C and 100C.
As for zinc, the Rotella T6 5w40 has 1200 ppm (0.12 %) zinc whereas the Mobil 1 0w40 is 1000 ppm (0.1%) zinc. So I'm sure either would be perfectly fine and not harm the cats.
As for zinc, the Rotella T6 5w40 has 1200 ppm (0.12 %) zinc whereas the Mobil 1 0w40 is 1000 ppm (0.1%) zinc. So I'm sure either would be perfectly fine and not harm the cats.
Thread Starter
Melting Slicks
Joined: Nov 2011
Posts: 3,183
Likes: 265
From: Virginia
I'm sure I'll get flamed for this but I run Rotella 15w40 in every LS I've ever had...I probably lose a half of a horsepower for it but the **** works and I've never had one with a bad looking bearing when I took them apart. The guy that told me to start doing this has probably had more LS platform cars than anyone I know, everything from trucks to cars to ls swapped buggies. Took his word for it and its worked well for me every since.
I would go with the Mobil 1 0W40 SuperCar. It's viscosity is higher than 5w30 at both 40C and 100C.
As for zinc, the Rotella T6 5w40 has 1200 ppm (0.12 %) zinc whereas the Mobil 1 0w40 is 1000 ppm (0.1%) zinc. So I'm sure either would be perfectly fine and not harm the cats.
As for zinc, the Rotella T6 5w40 has 1200 ppm (0.12 %) zinc whereas the Mobil 1 0w40 is 1000 ppm (0.1%) zinc. So I'm sure either would be perfectly fine and not harm the cats.
Le Mans Master
Joined: Dec 2013
Posts: 6,337
Likes: 5,115
From: Charles Town WV
2024 Corvette of the Year Finalist - Modified
2023 C6 of the Year Winner - Modified
2022 C6 of the Year Finalist - Modified
Thread Starter
Melting Slicks
Joined: Nov 2011
Posts: 3,183
Likes: 265
From: Virginia
lol well that may be true but I would probably be a little concerned with oil not flowing through the passages quickly enough especially on start up with that weight. I’m certainly no expert though so if that oil has been working good for you and all of your internals look good then I would just keep using it
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Le Mans Master
Joined: Dec 2013
Posts: 6,337
Likes: 5,115
From: Charles Town WV
2024 Corvette of the Year Finalist - Modified
2023 C6 of the Year Winner - Modified
2022 C6 of the Year Finalist - Modified
lol well that may be true but I would probably be a little concerned with oil not flowing through the passages quickly enough especially on start up with that weight. I’m certainly no expert though so if that oil has been working good for you and all of your internals look good then I would just keep using it