Amsoil 5w-30 once a year or Mobil 1 ESP 5w-30 twice a year?
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First, do whatever makes you feel better.
Second, I think the only way to find out is a UOA.
To me personally, I like ESP for its approvals. Also in my Kia (which is not comparable to the Vortec in any ways), I’ve tried both and subjectively, SS was no different from any other oil. But ESP is making the engine start, run and even stop so much smoother. Call it a placebo effect, but I own the car since brand new and change the oil every 3k miles. It’s at 45k right now and it has never ran this good. I’m sticking with the ESP now on
Second, I think the only way to find out is a UOA.
To me personally, I like ESP for its approvals. Also in my Kia (which is not comparable to the Vortec in any ways), I’ve tried both and subjectively, SS was no different from any other oil. But ESP is making the engine start, run and even stop so much smoother. Call it a placebo effect, but I own the car since brand new and change the oil every 3k miles. It’s at 45k right now and it has never ran this good. I’m sticking with the ESP now on
How many miles do you put on in a year and are they city, highway or mix?
Roughly 12-13k so not that much, mostly highway.
4WD
$50 site donor 2025
M1 EP + Fram XG … one n done 
Hands down the ESP, and take a sample of the oil in 6 months to see how it's doing. You might be able to extend the OCI to a year. IMO ESP is the best of the Mobil 1 line up. If you watch prices you can score ESP from NAPA from $4.99-$5.49/qt. a few times a year.
JHZR2
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Not sure why you couldn’t run the M1 once a year. Do you have any UOA evidence?
What sort of mileage are we talking about covering in this year?
4WD
$50 site donor 2025
Info above (12k-13k, mostly highway)
Assuming this is an actual inquiry for facts rather than an attempt to create another "Mobil 1 vs. Amsoil" thread, Castrol or Mobil 1 0W-40 from Walmart would be an entirely acceptable answer for less money than either of the two mentioned by the OP.
Lol, gotta say that's the first time I've ever seen the claim that an engine stops better on a particular oil.
When posters make claims like that it's hard to take anything else seriously.
Why does it have to be on a specific time schedule?
Change it when it needs to be changed.
Change it when it needs to be changed.
I think either one would be fine changed once per year.
Not really sure why you're considering the two choices you've presented. Both are intended for longer intervals, and you're not driving enough to exceed the mileage recommendation for those two oils. You're also well out of warranty, so you're free to choose an oil and change interval that suit you.
Not really sure why you're considering the two choices you've presented. Both are intended for longer intervals, and you're not driving enough to exceed the mileage recommendation for those two oils. You're also well out of warranty, so you're free to choose an oil and change interval that suit you.
And I do agree with that! That’s why I’ve said call it a placebo effect all you want
But with any other oil, when I push the “start/stop” button to stop it, the whole car gives quite a shake. I’ve never worried about it, thinking it’s just what it is. Now, after I changed it to ESP the car just shuts off, no more shaking. The difference is huge. Nothing else but oil was changed. So unless it’s a property of this specific model to stop doing so after 45k miles, I do think it has smth to do with oil
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