The ZZDPlus website pooh-poohs the diesel oils (and everything else except their product) due to excessive detergent package and inappropriate viscosities, among other reasons. The website is an interesting read but does not address why their additive adds $2.00/quart to the cost of an oil change while former and present lube oil vendors can blend it in for apparently negligible cost. At $2.50/ounce, it costs $320/gallon//$13,40/barrel. It is advertised on eBay, but at essentially the same price. One of the most interesting curves presented at the website is the concentration depletion with mileage. It's almost as if the ideal situation would be to bring the concentration up to minimum, then maintain it by adding a few drops every few miles. Like good old Marvel Mystery Oil (except that went into the intake manifold). Bottom line for me is that it is still pretty cheap protection, especially if one can buy oil with enough zinc in it to protect our high performance engines. I'm going to find some for both my '55 C-300 and my '86 LeBaron T&C with 2.2 turbo and catalytic converter. Replacing the cat should be cheaper than a rebuild. Michael: Where do you find spec's on ZDDP content for the oils you favor? Went to a local car show today, judged by entrants. Beautiful venue near waterfront in Benicia, CA. Results: Fords: 19 Chev: 15 Dodge: 2 ('68 & '70 Chargers) Olds:2 (Both '50 coupes, 1 Best of show) Chrysler: 1 '38 Royal with rat motor (2nd in class-nice old 4-door Royal-street-rodded, but stock body-folks do appreciate something different) Cadillac: 1- '49 Fastback, first in class Now, if I bagged our C-300, painted it metalflake red, chopped the top, installed a supercharger and a custom interior, chromed the engine compartment--do you think those Ford and Chevy owners would vote for it--maybe. Would you? No. Case closed. There was a rather interesting '62 Chrysler "Newport" there, highly customized and chopped--metal flake green, custom interior. Kinda reminded me of those overweight and overaged actresses that try to compete with the young hotties. Two separate classes and never the twain shall meet. I met a guy whose dad used to own a '55 Chrysler 300, except it was blue and a convertible. Happens all the time. Folks remember and appreciate the style and the reminiscences that flood back with viewing our car. And a few kids really think the car and its "dagger-on-the-dash" are cool. That makes it a good enough day for me. I met a new 300 Club member there (sans car, but at my invitation) and he is thrilled with his new purchase of a red F coupe. He and it will be a contender after restoration. Did some 80 on I-680 and it seemed to be just leveling out. I put 30 psig in the L-78x15 Remingtons and the ride was a little firmer and harsher. Questions: Anyone have a set of the AMA specs that I could get a copy of? I'm most interested in the spec's for ENGINE-EXHAUST SYSTEM-Exhaust pipe diameter and Tail pipe diameter. This month's BRUTE FORCE publication has the '56 AMA specs and they are as follows for the C-72-300 (300-B): Exhaust pipe 2.25" Std, 3.0" Opt (Rev 12-5-55) Tail pipe diameter 2.0 (Rev 12-5-55) '56 NY was 2" and 1.75" for duals, Windsor was 2.5" and 2" for a single exhaust with a 2" crossover. Duals offered as special equipment. 4-bbl carb was "Power Package" on Windsor 331 poly. The parts book seems to indicate the exhaust pipes for '55 & '56 300's are the same, but the tail pipes are different. Any insights on proper diameter before I have some new aluminized steel tube rolled would be appreciated. C-300'ly, Rich Barber Brentwood, CA (high 80's and low 90's here (temperature, not speed!) 1955 Chrysler C-300 (nicely waxed and looking about as good as it could in off-spec white--and aren't wire wheels fun to detail?) -----Original Message----- From: Chrysler300@xxxxxxxxxxxxxxx [mailto:Chrysler300@xxxxxxxxxxxxxxx] On Behalf Of Michael Reed Sent: Sunday, April 27, 2008 5:16 AM To: chrysler300@xxxxxxxxxxxxxxx Subject: Re: [Chrysler300] ZDDP re-visited-the bottom line We hashed this subject to death a few months ago. I want to point out to the group that Bruce is mistaken in his post, where he stated, "All of todays oils now have zero zinc..." and "...by 2004 no oil has any zinc as per EPA." There are several companies which produce and sell motor oils which contain appropriate amounts of ZDDP for our 300s (and other autos of the period). They are motor oils which are directed to the diesel engine market. Mobil and Shell are two of those companies. I use Mobil Delvac 1300 Super in my "F" and in my '70 Chevelle LS-5 *without reservation* -- there are more than adequate amounts of ZDDP in that product (as well as other benefits). Shell Rotella T is nearly identical to Delvac 1300 Super in it's specifications, including the amount of ZDDP it contains. Both of these products are available in 10W-30 and 15W-40 viscosities. Mike Reed in Lake Odessa, Michigan ----- Original Message ----- From: Gnspeedbird@xxxxxxx To: chrysler300@xxxxxxxxxxxxxxx Sent: Saturday, April 26, 2008 22:45 Subject: [Chrysler300] ZDDP re-visited-the bottom line For the past month and particularly this past week the subject of ZDDPLUS has been thrashed about but not been totally resolved. Simply put all flat tappet engines need a zinc additive .All of todays oils now have zero zinc,thus jeoparadizing the life of our engines..Fortunately ZDDPLUS has been developed so that one 4oz bottle added at an oil change will have the exact zinc content contained in oils up to 1985. Since the mid 90's the zinc content has continually been decreased so that by 2004 no oil has any zinc as per EPA directives.Every member of this club should educate themselves about ZDDPLUS by going to _www.zddplus.com_ (http://www.zddplus.com) most of your questions will be answered on this site. We are very fortunate that one concerned car collector footed the bill to develope a product that will save an untold number of engines. There are many ZDDPLUS distributors throughout the country. PTS Xtreme at 916-739-0510 has ZDDPLUS in stock.......Bruce Toelle **************Need a new ride? Check out the largest site for U.S. used car listings at AOL Autos. 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