Another What Oil do u use thread

[Ccmano]

Did a little research today. My 1990 owners manual specifies 10w30 type “SG” spec oil for the ZR-1/LT5. On the website Bobistheoilguy.com site I found the original ZDDP spec for type “SG” spec oil was at level of 1000 - 1400 ppm back in the 1990’s.
https://www.bobistheoilguy.com/forum...71&type=thread

I assume therefore that the original minimum engineering spec for ZDDP is probably ~1000ppm. It is also probably safe to assume that any oil with a ZDDP spec of 1000ppm to 1400ppm that otherwise meets “SG” spec. is correct.

That said, I still believe the concern for ZDDP levels in our cars is wildly overblown. The original failures reported were exclusively in high performance push rod flat tappet engines with high lift cams and extraordinarily high valve spring pressures. While our engine may have “flat Tappets” or buckets our valve spring pressures are less than half of those where these issues showed themselves. When they talked about “flat tappet” engines Overhead Cam engines were not in the mix.

Should we err on the side of caution, by all means. It is certainly wise to make sure the oil we use has at least 1000ppm of ZDDP. Conversely, those that don’t are certainly not in imminent danger of cam failure. My guess is that most of the ZR-1 currently running around today are on a modern oil like Mobil One with the lower ZDDP rating. We certainly don’t see cam failures left and right. As a matter of fact cam failures remain exceedingly rare.

That’s my 2 cents, your mileage may vary.
H