Hey guys …I’m pretty sure I already know what the majority of answers will be here but I’m interested to see if anyone agrees with some local answers I’ve gotten…

so I have a 1981 cream-puff that had a Jasper Engines rebuild (using the original engine) in 2005.

The car has 9000 miles put on it since the new engine install. The last oil shop sticker was still on the windshield so I called the number and got the info of what oil was put in it. Pennzoil Platinum 10w30 full synthetic. At least two oil changes with that oil.

So now let’s go down the ‘Zinc’ rabbit-hole. The car is 100% completely stock with the CCC and the stock catalytic-converter. High Zink causes CC damage so I’m told.

long story short is I’ve been told at least twice that a low-compression flat tappet motor with stock valve-springs that’s already broken in with 9000 miles will do fine with the Pennzoil Platinum.

Thoughts?

 

I would follow the oil recommendation from GM... by that I mean use an oil with the zinc level that was common in 1981. That means something along the lines of 1200ppm ZDDP. Lower zinc levels became a thing in the late 1900s ( 😉 ) and all sorts of things started to go wrong with engine wear.

 

Thanks for the quick reply!

I see that the oil of choice seems to be Valvoline VR1. The container on that oil says “not for use in vehicles with Catalytic Converters”…

🤷‍♂️

 

Mobil 1 classic is specifically designed for cars of this age (up to 1996).

 

Depending on where you live a catalytic converter is a lot easier to fix than a flattened cam with metal shavings all in your engine.

Corvette Central

 

Thanks for the reply …just looked it up and read some posts about it. And of-course someone posted that it says “Does not protect Catalytic Converters”…

Of course lol …such a grey area …the use of flat tappet cams that require Zinc but also using Cats that Zinc destroys.

 

In my younger days I would’ve done just that but this car is so unmolested I don’t want to hack it up. It’s quiet and smooth and drives and sounds like you’re driving it off the Chevrolet dealership parking lot.

I can idle the car in my shop and not smell a thing …although I do start feeling light headed still
🤣🤣🤣

 

I know what you mean. But the Mobil site says this:

Between this and the 1996 date they include in their literature, I take it to mean that the more modern OBDII smog equipment is more at risk of damage from zinc. Certainly your car was built while oils still had high levels of zinc. So, I think this oil should be fine for your car.

 

Yep …I’m gonna go with the Mobile 1 Classic. Just watched this video which made me feel better…

 

GM (and its brethren) effectively solved the Zinc versus Cats conundrum when it began fitting sbc/BBC (and newer designs) with roller cams + roller lifters.
That cam-lifter design change effectively ended requiring oil containing high Zinc + Phosphorus wear packages.

Tens of thousands of enthusiasts retro-fit their old iron w/ roller lifters + roller cams.

OR, you Must feed your existing flat tappet cam and flat tappet lifters a diet of oil that's rich in both Zinc AND Phosphorus. Valvoline VR1 is widely available, affordable and quite popular.

* Even NASCAR followed suit. No Cats there, but CUP was the last holdout of the NASCAR trinity. CUP was last to do away with flat tappet filters. Considerably Lighter flat tappets can make more power at higher revs; but at great $$$ cost of constant replacement w/ bits made of exotic metals/treatments + exotic oils.
It is simply much cheaper to run rollers And limit revs. They (CUP) ALL do so; as do the lower two rungs.

** believe this: that oil & lifter situation also hasn't bypassed the grassroots endurance racing industry/hobby either; where there's far Less money to go 'round.

 

Thanks for the reply. Yea I’ve already ordered the Mobile 1 Classic which wasn’t cheap but I’ll only be changing the oil on this car once a year.

like Piersonpie said it’s easier to replace the cat than the engine. If the cat ever fails I’ll bolt in a test-pipe of the same length. The CCC apparently doesn’t need the Cat as long as the O2 sensor is still installed and working…

 

Have you considered Driven Oil?

 

Just got the Mobile 1 FedEx yesterday. See how it goes. Ecklers has 81’ CATS for $240 so if it fails not that big of a deal. Or could just bite the bullet and so true duals …Corvette Central has a kit with the bung for the O2 sensor.

https://www.ecklers.com/1976-1981-co...iABEgKXA_D_BwE

 

I don't think you'll have any problems. Your O2 sensor is upstream of the cat. If you do ever have to replace it (in 100K+ miles), you'll want to convert to a true-dual with twin high-flow cats anyway.

 

I use Driven hot rod 10w40,

 

Personally, I use Mobil 1 or Castrol Edge European Formula ONLY 0W-40 in every single combustion engine car, generator, snowblower, lawn tractor, etc.....period...regardless of what oil is specified by the manufacturer (There is a lot more to OEM oil recommendations than is apparent). These oils (and others) and grade have superior viscosity indexes (oil stability over the complete temperature range and longevity) as well as Zinc level of approximately 1,000/1,100 ppm, plus a superior additive package.

The reason the EPA reduced the Zinc levels many years ago to around 800 PPM was to prevent "poisoning" the cats with the higher zinc levels and mainly to force the OEM manufacturers to extend the warranty for the emissions system from 5 years/50,000 miles to 8 years/80,000 miles. Most cats even with much higher zinc levels above 800ppm last a VERY LONG time, even today, well beyond these ranges.

My recently departed 2001 Grand Prix that ran Mobil 1/Castrol Edge 0W-40 European Formula most of its 240,000 mile life before going to the crusher with the OEM cat still on the car and functioning (car rusted out), ran and shifted perfectly. OEM cat still going strong (22 years old). Same deal on my 2008 Chrysler 300 3.5 V6 with dual cats, same oils, currently at 180,000 miles, with emission system perfectly fine with no "poisoning".
My 10 C6Z06 LS7 also runs only 0W-40 European Formula high zinc oil with its dual cats....I am more concerned about the irreplaceable LS7 427 aluminum engine than any concerns about "poisoning the cats....
I have never had a cat fail from high zinc levels. Like most things in life, especially now days, there is a story versus the real story...........