When searching; you can find a lot of PFF threads on this subject……
However, I wanted to remind ‘newer’ Fiero owners when I saw this 2010 'MotorTrend' article:
“An epidemic of cam failures has plagued owners of older cars recently.”Flat-Tappet Cams and Worn Down Engines - The Perfect Storm
https://www.motortrend.com/...8-worn-down-engines/"Our primary goal here is to warn readers who own flat-tappet cam engines that there are new choices to be made concerning the oil that's put in the crankcase in order to avoid premature cam failure.
A second goal is to inform readers who are thinking about rebuilding their motors {by} installing a retro-roller cam and valvetrain."
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Engine Oils Have Changed Over Time from the Fiero EraThe API SF rating on my 1988 V6 was critical for the flat-tappet lifters/cam engine.
1100-1400 ppm Zinc
1000 ppm Phosphorus
I started with an API SF Valvoline oil decades ago; unfortunately, but this rating is now considered 'obsolete'.
As a summary in the link above:
These anti-wear additives in 2024 engine oils have significantly decreased, yet
nowhere is this mentioned on the label!
A reason for the reduction is to ensure catalytic converters last longer. Eventually, trace amounts of these additives will get past the rings or valve guide seals and go into the exhaust and will damage the CAT.
Because I'm on my third CAT at 136k miles AND California-compliant catalytic converters for a Pontiac Fiero GT are big $$$; I'm attempting to 'balance' Cam and CAT damage by using 'regular' Castrol GTX now which is an API SP-rated oil:
900 ppm Zinc
700 ppm Phosphorus
And of course, I change the oil at 3k miles.
Many members are posting that they're still using 'High Zinc' oils, which the 'fine print' says "Not for use in engines with catalytic converters."
(I guess they don't have CATs.......or they're 'cheaper' than CAT's in California.) Also see the section in the link titled:
"Synthetic Oil - There are two sides of the argument about the danger of running synthetic oil in a flat-tappet cam engine."
I'm betting that many members will chime-in on the thread.......
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Original Owner of a Silver '88 GT
Under 'Production Refurbishment' @ 136k Miles