73-87 Chevy _ GMC Trucks > Engine/Drivetrain

Engine Oil for Flat-Tappet Cams with Catalytic Converters

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darrenbenjamin73:
I'm just starting out as a DIY weekend wrencher. I have two classics--a 1980 C10 SBC 350 w/cat. converter (mine) and a 1979 Trans Am w/Olds 403 w/cat. (wife's). I've read up on oils with high ZDDP for flat-tappet cams and the supposed problems they cause for cat. converters. So far, I've found no products on the market for this situation. That said, I've also read that broken-in cams do just fine with modern oils.

If you're in this situation too, what do you do? If you're otherwise an expert on the topic, what would you recommend?

JohnnyPopper:
I'm not much help with your question...But

Welcome from SoCal San Diego- the land of Fruits and Nuts.

I wasn't aware of any interaction of ZDDP and Cats...look forward to seeing how this develops.  ;)

Captkaos:
I would assume that the 80 and the 79 have factory catalytic converters on them, and if that is the case they are the old style that were used with zinc in the oil.  New catalytic converters are denser with less catalyst and can be clogged but unless the vehicles are burning an excessive amount of oil it shouldn't matter.
ZDDP is an additive for oil for flat tappets, when they are being seated during break-in is the most critical time, if these are original equipped I personally would use oil with zinc like Amsoil or Lucas if you have concerns around wear and want to keep them original.

VileZambonie:
STP oil treatment is less than $5 bucks. Add it to each oil change and you're good to go.

Swampyankee74:
On the pricey side. But this should do you...

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