Sulfurized Esters

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I am getting my 1972 Plymouth Road Runner 440 out of a multi-year hibernation. I am reading through the service manual and for the 440 it says to add a can of Mopar Sulfurized Ester High Performance Additive to each oil change. The recommended oil is either 20w-40 or 20w-50. The oil part is easy. But what is sulfurized ester? Is it still needed in this engine after 45 years? Has oil technology improved so that I don't need it? Will the base oil would be fine? I did a Mopar search for sulfurized ester additive and it is long gone out of the parts book. Any advice would be appreciated. I welcome any opinions on the engine oil too. Thanks.
 
Just run a good quality oil meant for Flat Tappets and you will be fine. I would suggest a 5w40 or a 5w50 in Michigan if you intend to run in cold weather or a 10w40 / 20w50 in warmer temps.

Amsoil Z-Rod is a good choice or something similar.
Although it's labeled a 20w50 it flows really well in cold weather. (-40F is the pour point)

https://www.amsoil.com/shop/by-product/m.../?code=ZRFQT-EA
 
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Sounds like something from back in the day that's been far superseded by better chemistry.
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That is what I am thinking. The chemistry has got to be much better today especially with synthetic oils.
 
Originally Posted By: Building3
That is what I am thinking. The chemistry has got to be much better today especially with synthetic oils.


For Sure
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Looks like sulfurized esters can be Extreme Pressure additives, maybe a dose of some MoS2 might be a good substitute?
I'd definitely get an opinion from one of the formulators on here before acting on any recommendation from me, I'm a pure amateur.
 
Royal Purple's proprietary Synerlec additive has been theorized on BITOG from time to time as being some kind of a sulfurized ester. It is still in their HPS and racing oils. But not in their ILSAC grades.
 
I was still at school in 1972 but I can think of a few reasons why they wanted you to add this can of Sulphurised Ester.

The first reason is they might just have wanted you to add Ester to the oil as a 'synthetic' base oil. Remember back then, Group I base oils were the norm and early Group I 20W50s wouldn't have had a great deal of resistance to oxidation. However most esters have brilliant resistance to oxidation. The problem with all esters is they are extremely expensive and most of the oil marketers would have been highly resistant to putting them in run-of-the-mill oils. Getting the owner to buy the ester separately might have simply been a way to get around this.

The second reason is that they may have viewed the Sulphurised Ester as an Antioxidant additive. I've never used them as such but I have plenty of experience using Sulphurised Olefins as Antioxidants (in both cases, you're simply using H2S to saturate a double-bond on an backbone). I can't say I'm a great fan of Sulphurised Olefins AOs (they're very smelly and aren't great on seals) but if you're chasing TEOST in a heavy Group II oil, they're often the most cost-effective additive fix.

I don't think Sulphurised Esters would have be seen as an Extreme Pressure fix. You might use something like Sulphurised-PIB for Gear EP but absolutely not in PCMO.

I'm not sure what to recommend for your Plymouth. I would deffo stick with 20W50; don't go thin. The trouble with US 20W50s is they're not very good for what you want (Group II with low ZDDP). What you really need is a nice Middle-East Group I 20W50 SL/CF oil (or better still 20W40). Strangely something Iranian might be perfect for your needs!
 
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