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My current project is getting my old Dodge pickup back on the road. I picked this up from their email list. May be of interest to the group here too:

Date: Tue, 24 Jan 2012 22:02:37 -0600
Subject: [39-47Dodge Trucks] engine oils

Bringing up this subject again,
I've been on the prowl looking for a replacement oil that I can carry in my shop for use in customer vehicles, as well as my own. I strictly work on pre 1970 auto and truck, and virtually all years of farm tractors with the bulk of repair and restoration work being done on vintage tractors. As most of you know, modern engine oils no longer can be used in older equipment due to the severe reduction and in many cases the complete omission of zinc rendering the camshafts and followers (lifters) completely unprotected and unlubricated leading to catostrophic failure. Many camshafts are no longer produced and the few that are probably won't be for long. To cut to the chase as it were: I recieved a positive reply from the folks at Castrol, many requests to other mfgr's yeilded negative. Below is the responce....
take it for what it's worth, I've been using 20-50 syntec for a while as a test in my '71 Beetle and am completely happy. now with the information supplied by Castrol I am switching everything over and will be using it on customer vehicles as well.

Ticket #9352

Inquiry on oil to use on flat tapped engines
Company: Castrol
Contact: Not Provided
Address: Not Provided

Detail Description:

Sat 21/01/2012/5:29 AM EST/ (email)
I run a small repair shop with the focus on pre 1970 auto and farm tractors, Modern oils are no longer formulated for flat tappet engines so we are forced to use additives to reduce wear (zinc) Ive heard that syntec 20-50 is an option, is this true? will it work foe example in the flathead chrysler 6, the flathead ford V8?
I'm experimenting with it in a 1971 volkswagon beetle, it seems to be handling the heat of the aircooled engine however i'm unsure of the antiwear characteristics, any insight?
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Problem Resolution:

Tue 24/01/2012/11:45 AM EST/ IC - Castrol Representative-
Thank you for contacting Castrol.
Classic cars with flat tappet cam engines represent a special case in regards to engine oil lubrication. These engines have valve train configurations that require elevated levels of zddp (zinc dialkyl dithiophosphate) anti-wear for proper protection of the flat tappet camshaft and its lifters. Insufficient concentration of zddp will lead to premature wear and failure of the camshaft and lifters. Current GF-4 and GF-5 fuel economy grade engine oils are designed for extended life of the catalytic convertors in modern passenger cars and have industry mandated limitations on the amount of sulfur and phosphorus within the oil.
Castrol SYNTEC 20W-50 classic car formulation has been replaced by Castrol with SYNTEC Power Technology 5W-50 viscosity grade. The 5W-50 grade has also been specially formulated for classic car use and has adopted the 20W-50 claims - designed for use in classic cars. The 5W-50 formulation contains more zinc additives than the 20W-50 and will also enhance start up ability in cold temperatures as well as enable better fuel economy.*
*Compared to SAE 20W-50.
Castrol always recommends following the guidelines of the original engine manufacturer for the recommended grade and API specific to your application. This information can be found in the vehicles owner's manual or by contacting the manufacturer directly.
Castrol Consumer Relations
Original Post

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I paid 10x that locally for Royal Purple (9 litres) since MME insists it's the only oil I should use. You yanks have it easy, everything available and cheaper than here in the semi-broke part of the world named after a Jovian moon...(look it up Smiler)

Seriously, my 100% orig 68 Camaro is of course flat tappet. What should I look for when reading the label on local oils to keep it alive? Zinc? So far I've just used cheap 15-40 without problems
Originally posted by No Quarter:
... here in the semi-broke part of the world named after a Jovian moon...(look it up Smiler)

Seriously, my 100% orig 68 Camaro is of course flat tappet. What should I look for when reading the label on local oils to keep it alive? Zinc? So far I've just used cheap 15-40 without problems

You live in Ganymede? Never heard of it! Big Grin

The oil bottles will generally not give any clue to their formulation, unless they say something like "high mileage" for seal swelling agents or "classic car" that may contain extra ZDDP. You might actually look into motorcycle oils. They tend to have higher level of ZDDP than automotive oils because they are intended to be used in vehicles that typically do not have catalytic convertors.
I called Valvoline a few years ago about their VR-1 racing oil, and they confirmed that it has the higher ZDDP. So it's another option (there seem to be a number of oils that have the higher ZDDP from Amsoil, Brad Penn, Royal Purple, Red Line etc, but just don't expect to find them on the shelf at a big-box store).

Here is what I was told when I called them in 2009 [1-800-TEAM-VAL ... 1-800-832-6825]:
- Valvoline VR1 20W50 contains 1400ppm Zinc and 1300ppm Phosphorus
- Valvoline VR1 30weight contains the same 1400ppm Z and 1300ppm Ph

There are hundreds if not thousands of web pages devoted to the whole ZDDP for classic cars discussion, the consensus seems to be to avoid modern oils formulated for cars with catalytic converters (those with 800ppm or less of ZDDP), 1200-1500ppm seems to be the sweet spot, going above 2000ppm and people start arguing about potential negative effects.

VR-1 goes for $8-9/litre here in Canada, not great, but not bad I suppose ... at least they don't have to ship all the way to a Jovian moon (If not Ganymede, perhaps Io?).
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