You are correct that that was an older document. It was superseded in 2011 by 20-24C, which curiously made no mention of additives. It was then superseded by 20-24D on 6/30/2014 with additives covered again. The wheels of bureaucracy have been spinning wildly.
http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC-20-24D.pdf
Quote:
(2) For additives not incorporated into an ASTM, SAE oil standard, or a brand name that meets an SAE standard, governmental or military specification, or other industry-based consensus organization specification:
(a) If the FAA determines that a demonstration of compliance for each certificated product for which the additive is intended to be used on is necessary, then the applicant must follow the process described in paragraph 7.f. of this AC to add the additive to each product's TCorSTC.
(b) In special cases, the FAA may determine that sufficient data is available to support a broad-based approval for use of the additive on unidentifiable population of engines o raircraft. For example, an additive with an identical composition to an existing, approved additive may have extensive service experience on a specific category,or type of aircraft or engine. Int his case, the FAA may conduct the evaluation and approval in accordance with § 21.8(d).
(c) For approvals conducted according to paragraphs (a) or (b) above, the showing of compliance must address the following:
1. It must be demonstrated that the additive does not have any adverse effects on the operation, performance, durability, or materials of the products intended for use.
2. I t must be demonstrated at the additive does not have any adverse effects on the performance of the base fuel or oil that it is intended for use with.
3. It must be demonstrated that the additive is compatible with an other additives, or combination of all other additives, permitted for use in the base fuel or oil that the additive is intended for use with.
The FAA does not test the fuels, oils, or additives. It is up to the manufacturer to submit the results of the required testing to the FAA. It is all on the manufactures dime. They only have to submit data to satisfy the FAA on points 1-3 above. Again, no proof of efficacy required.
CamGaurd does hold certification for use in non-turbocharged engines. The FAA is requiring CamGaurd to do the endurance testing on turbocharged engines. It is up to CamGaurd to do that testing and submit the data to the FAA to obtain certification for that type of engine.
Ed