Don't have the GM part number handy, right now. If you have AC/Delco parts dealers down there, the AC/Delco part number is 10-106

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

E.O.S. PT.NO. is 1052367. Castrol Tection 15-40 still has a CI-4 Plus rating.
STP has alot of zinc in it and have heard of it being mixed with oil for use as a assembley lube,what about its use as a an oil additive to replace the zinc?
n HyperValiant

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1960 Hyper-Pac Valiant(rolling test-bed)
1963 Valiant V2OO(Son's summer project,- he just turned 15 )
1972 Valiant 4dr(Daughter Kelly's repair in progress)
1974 Valiant (v8) daughter Kelly's work in progress

I don't know about STP now, but in the past it was thought to cause heavy varnish deposits. It's primary purpose was a viscosity "improver." That is, it made oil thicker which is not what you ordinarily want or need. I know nothing about it's zinc content.

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David Kight
'62 Valiant Signet, White
'98 Dodge Dakota
'06 Jeep Liberty

Growing older is unavoidable but growing up is strictly optional.

I jumped on the Rotella bandwagon after Mobil-1 Extended Performance got emasculated with the API SM limits on additives (it used to be that M1 Extended still had the SL rating, while "regular" M1 got the SM, but that's no longer the case).

Unfortunately, it is ALSO no longer the case that Rotella T 15w-40 has an SL rating. Its gone to SM as well, and what's worse it lost its CI-4plus rating and is now rated CJ-4

Shell Rotalla Synthetic 5w40, at least the bottles still on shelves at the stores I checked, is still rated CI-4plus, so buy in quantity while you can. If you can live with a conventional oil with a 15-40 rating (I don't want to waste that much power, and with a high-volume oil pump in a v8 you don't have to worry about stripping the drive gear) then you can still get Chevron Delo400 and Mobil Delvac 1300 with a CI-4 plus rating. Mobil Devlac1 5w40 is a synthetic that also meets CI-4 plus and API SL (not SM, which is the "bad" one for flat-cam engines).

But the bottom line is that ALL oils, including the "good" diesel oils like Rotella, Delvac, and Delo, are all going to get their zinc levels reduced in coming years. The good (sorta) news is that the diesel oils will probably continue to have better cam protection since there are still a whole lot of flat-tappet diesels out there in the wild that need protection, even if they have to do it with other additives than ZDDP. The "better" news is that the whole issue is probably not that much of an issue with stock cams. Its the high-lift, high-rate cams that have to run monster valve springs that see the real problems. And there are other things being worked too. At least one lifter manufacturer is now drilling a small oiling hole right on the cam contact face of the lifter to greatly increase the amount of oil film available. Plus "beehive" springs are becoming more popular because they're much easier on cams.

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