What is "Plan B" if I can't get Amsoil Z-Rod for My 1990 Corvette ZR-1.

Jackson_Slugger

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The Mobil 1 HM was reformulated years ago and is no longer higher in ZDDP - it is around 800 now.

Summit Racing has plenty of high ZDDP oils to choose from and Valvoline VR1 is available in a full synthetic as well. I don't think you need the high ZDDP in the LT5 or any GM engine of the C4 era for that matter. My 94 LT1 runs just fine on Mobil 1 and remember in 1992 all Corvettes came factory Fill with Mobil 1 - LT1 and LT5 so GM is saying with that spec alone that high ZDDP is not needed. So rest well and I would just run the full synthetic of your choice be it Mobil 1, Pennzoil, Amsoil etc.

The 10W-40 still does, it's about 1000ppm as is FS 0W-40, the latter would be my choice even if the extra zinc isn't needed here...

 

FCD

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I'd use Mobil 1 0W-40, Porsche A40 approved, about 1000-1100ppm of Zddp, which is enough, and also in Canada it would really be ideal being a 0W, although i assume it probably doesn't see salty roads much :)
 

Arrow

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The Porsche A40 approval suggestion is more than appropriate here. It’s a far more demanding requirement than what was the API license you’re referencing. More than one example is available at Walmart for a very reasonable price. Other suggestions in this thread are “experimenting” but this one is not.
Thank you. Yes, I’ve been taking the A40 recommendations seriously, and have been doing some research On it.
 

Arrow

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I'd use Mobil 1 0W-40, Porsche A40 approved, about 1000-1100ppm of Zddp, which is enough, and also in Canada it would really be ideal being a 0W, although i assume it probably doesn't see salty roads much :)
It does get regular starts in the winter, but not any driving. 3400 lbs, rwd and 315 wide tires would make for an interesting snow road experience. :)
 

Arrow

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The 10W-40 still does, it's about 1000ppm as is FS 0W-40, the latter would be my choice even if the extra zinc isn't needed here...

Old guy thinking on my part, but I guess I automatically discounted 0W oils from my mental checklist. I was looking for at least a 5 or 10. Old habits and all.
 

Astro14

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I would use the Mobil 1 0W40 that meets A40 and MB 229.5 in a heartbeat.

Like others on this forum, I’m a big fan of HPL, and use their products (for which I happily pay) but it seems to me that your challenge is availability.

That Mobil 1 should be readily available, has had good UOAs for me, and I use it in a pair of engines that are very, very expensive to rebuild.
 

Arrow

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No thoughts on the Liqui Moli? Seems a good option from what I’ve been reading around here,

72A55938-459A-4BFE-AA14-5C1A58A80EDB.jpeg

https://www.amazon.com/dp/B00CPL952G?ref_=cm_sw_r_ud_dp_SQFRZHN44JZYCGDNSZ6J
 

Arrow

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I'd use Mobil 1 0W-40, Porsche A40 approved, about 1000-1100ppm of Zddp, which is enough, and also in Canada it would really be ideal being a 0W, although i assume it probably doesn't see salty roads much :)
And, sadly, the A40 approved Mobil 1 0W-40 isn’t widely available around here. The many joys of living in Canada.
 

Astro14

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Liqui Moly makes good oil, but I wouldn’t choose that one. I would get their 0W40 or 0W30 full synthetic that meets MB 229.5 and Porsche A40.
 
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Can you find Castrol Edge A3/B4 0W-40 or 5W-40? Both of those have Porsche A40 and MB-229.5 approvals.

This particular Liqui Moly engine oil would also be good, assuming available to you. It has recently been renamed as Synthoil A40, and carries the Porsche A40 approval:

 
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