Originally Posted By: Or

Originally Posted By: gryffinwings
I think I will consider a 10w30 for a rebuilt D16A1. I'll likely stick with Pennzoil though, I like the idea of more pure oil base refined from natural gas.
I agree. The idea of the Fischer-Tropsch GTL process is really appealing. But I haven't been able to translate that into world-beating performance, yet. And I don't think anyone else has yet, either. I tried Pennzoil Platinum 10w30 (not HM) in two alternate OCIs (7,500 each) with Mobil 1 High Mileage 10w30 in between (and before and after, it has been my regular oil for a while now). I saw a slight increase in oil usage over the interval with the Pennzoil Platinum = 1 qt vs. about .5/.6 qt with the Mobil 1 High Mileage. I did this twice to confirm. That alone is not a reason to NOT use the oil, but others I have read here also note a slightly higher consumption with Pennzoil Platinum for some reason. This was a few years ago before the Pennzoil PlatinumHM was available, and I haven't tried that yet. The HTHS on the Pennzoil Platinum 10w30 was more like a 5w30 (e.g., something like 3.1 I believe), and that came from an independent test because Pennzoil doesn't release it. I could tell a slightly quieter operation with the Mobil 1 High Mileage. I went back to the Mobil 1 High Mileage on a permanent basis and since then and I haven't yet tried the Pennzoil Platinum 10w30 HM.
It's a little frustrating as M1 won't give you their noack, but will give you the HTHS. Pennzoil doesn't release either so you have to catch data from independent test, which is spotty. You can't make an informed data-driven decision. I'll try the Pennzoil Platinum 10w30 HM sometime soon, but I'm not expecting it to be as stout as the Mobil 1 High Mileage, frankly. The lack of ACEA certs and reluctance to release all specs makes me less eager to try the Pennzoil Platinum again. I have a no reason to doubt it is an
excellent oil, but maybe just not "best in class," yet.
Now, for your application, 10w30 is likely a good grade to focus on. After that, do NOT be limited by HM vs. non HM. Hm will have, vs non, somewhat more seal conditioners (they all have them), and usually more dosage of ZDDP and there anti-wear additives you cannot put into modern oils because of mileage-driven requirements. I just don't think that applies to an older engine. For example, M1 kept the 10wXX HM variants "SL" rated (which was superseded in about 2005) until just last year. They didn't care about the current "SN" rating in order to provide more protection for older engines. As background, the newer oil ratings reduced the level of certain anti-wear additives that could be used in order to meet emissions goals - NOT because it's good for the engine itself.
I picked up Mobil 1 High Mileage 10w30, since there wasn't any 10w40 High milage I wanted to use, Mobil 1 high mileage 10w30 is now API SN. I wonder what changed, I think I will send in a VOA sample to Blackstone to see what's up.