Originally Posted By: A_Harman
Also, check out the above link. ZDDPlus has a lot of articles on their website about using zinc supplements versus other options for protecting slider-follower valvetrains.
We've all read that, but they gloss over a couple things. One, they're selling a product. Telling people to buy an HDEO, or Amsoil, or RP HPS, M1 racing, or Valvoline VR-1 cuts into their profit margins.
Secondly, although this was written in 2008, they claim limited viscosity choices for HDEO and no ILSAC rating. Well, do they want an ILSAC rating (with a corresponding reduced phosphorus content) or don't they? They can't have it both ways. As for viscosities, are they sure they didn't write this based upon 1988 oil choices? For HDEOs, there are 0w-30s, 5w-30s, 10w-30s, 0w-40s, 5w-40s, and 15w-40s readily available, under various Cx/Sx specifications. ZDDP levels are sufficiently high, and independent evidence of this abounds.
To them, HDEOs have too much detergent and this inhibits the effectiveness of ZDDP. I have no idea whether or not this is true. They cite one study, which has no link, and I haven't happened to come across to check it out. They mention energy conserving oils and viscosity choice, again, with respect to fuel economy. Does the price of their product added to the price of a PCMO save enough gas to make it a better option than, say, Rotella 10w-30?
Then, they claim that racing oils have too little detergent. We already know that. If it's a garage queen, does it matter? If it's never driven hard in the first place, does the ZDDP level matter much anyhow?
I don't claim that ZDDP supplements are ineffective or are inferior products. I've used Comp Cams additive, and still have a couple bottles left. It's far from the only option, however.
My view is that the people who would benefit most from a ZDDP additive (both for engine protection and financially speaking) are a rather niche market. Someone with an extremely high performance engine that tends to be driven only rarely and driven hard (i.e. weekend tracking, time trials, and so forth) would be best served by a racing oil. Someone who has an older, yet relatively mild engine that's driven regularly (i.e. as a daily driver) would do fine with HDEO or something like Defy (or even SN/GF-5 PCMO, for that matter). If you're running a high horsepower late 1960s/early 1970s high performance American car as a daily driver, then I can see the cost and protection benefit of a modern PCMO with a ZDDP additive. In this scenario, it would be far cheaper than a boutique oil with enhanced ZDDP levels.
I apologize for being so long winded about this, but old flat tappet engines see vastly different usage and maintenance regimens, with no warranty constraints, and there is no one size fits all answer with respect to return on investment. Lots of guys with older Jeeps run HDEOs with no cam problems. Also, lots of Chevy guys have run small blocks with high ZDDP oils and still saw cams get rounded out. I know; I'm one of them.