There's some good advice given in this topic. There is no need to run stiffer springs than recommended by your cam manufacturer. Excessive spring pressure doesn't benefit camshaft life.
HDEO is an excellent choice for older engines with flat-tappet valve trains. High levels of ZDDP don't necessarily contribute to greater valve train protection because the ZDDP layer doesn't become thicker with higher ZDDP concentrations. According to a
GM Techlink service bulletin (December 2007), Bob Olree GM Powertrain Fuels and Lubricants Group), excessive amounts of ZDP is not beneficial:
A higher level of ZDP was good for flat-tappet valve-train scuffing and wear, but it turned out that more was not better. Although break-in scuffing was reduced by using more phosphorus, longer-term wear increased when phosphorus rose above 0.14%. And, at about 0.20% phosphorus, the ZDP started attacking the grain boundaries in the iron, resulting in camshaft spalling.
The current CJ-4 and CK-4 categories phosphorus limit is 1200 ppm and this concentration has been found to work well to protect flat tappet camshafts. ZDDP additive manufacturer ZPlus also suggests a target of 1200 ppm of phosphorus: see
ZDDPlus™ Tech Brief #2 - ZDDP and Cam Wear: Just Another Engine Oil Myth?
An important consideration in choosing an oil is to make sure that it not more viscous than necessary. While heavier grades tend to have better
HTHS ratings, they also tend to not flow as well in cold temperatures. If you notice that your oil pressure is taking longer to come up in cold weather, you should probably be using thinner oil. While your pressure is building, there is more of a chance that the valve train in the boundary or mixed lubrication regimes and relying on the ZDDP tribofilm for protection.
If you're looking for a 30-grade HDEO, remember that these dual rated oils (API CK-4/SN) have a maximum of 800 ppm of phosphorus. For 30-grade oils, look for ones that meet CK-4 and are
suitable for SN.
PC Duron SHP 10W-30 meets Ford WSS-M2C171-D, which means it has 1000+ ppm of phosphorus.
See
Engine Wear