Dear Mr. Drummond,
Thank you for contacting Castrol North America.
As indicated on our product packaging, the current engine oil category API
SM/ILSAC GF-4 is fully backwards compatible or 'back serviceable' and has
been extensively tested. Valve train issues are not anticipated with the use
of modern engine oil in older cars of OEM stock configuration. In fact,
current SM/GF-4 engine oils are subjected to testing that is far more
intensive than engine oils of previous API/ILSAC categories.
To clarify, in general, ZDDP levels have been reduced a small amount in the
current category engine oils (API SM/ILSAC GF-4) in compliance with industry
regulations that set maximum levels of Sulphur and Phosphorus, but are still
at levels that provide ample engine protection.
Special procedures have always been recommended for the proper initial
break-in of a new, matched, cam and lifter set; which include the use of a
properly formulated cam break-in lubricant paste which typically contains a
healthy dose of molybdenum. Engine oil alone is typically insufficient for
break-in of a new cam and lifter set, particularly in a vintage engine type
built to historic specifications.
In regards to concerns with camshaft failure, Camshaft failure can be
attributed to numerous possible causes. Only a thorough analysis of each
case can identify the root cause(s) of any failure.
In regards to issues related to flat tappet cams in OLDER performance
engines typically known as MUSCLE CARS (NOT modern performance vehicles), we
can recommend the following Castrol Products ...
* GTX 20W-50 (SL,SM)
* Castrol GTX Diesel 15W-40 (CI4,CH4,CG4,CF4,CF,SL)
* Castrol GTX High Mileage 20W-50 (SL,SM)
* Castrol HD 30 (SL,SM)
* Castrol HD 40 (SL,SM)
* Castrol Syntec Blend Truck 15W-40 (CI4,CH4,CG4,CF4,CF,SL)(Semi-synthetic)
* Castrol Tection Extra 15W-40 (CI4Plus, CI4,CH4,CG4,CF4,SL)
* Castrol Hypuron S 15W-40 (CI4Plus,CH4,CG4,SL)(Semi-synthetic)
We trust this information addresses your concerns.
Thank you again for your interest in Castrol, The Technology Leader!
Castrol Consumer Relations
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