Won't that ZDDP be bad for his catalytic converter

 

Not sure but many years ago I had mine removed before most shops refused to do it!!!
JJ78

 

Fortunately most of those stupid mandates are on the way out.

 

1. Could be.
2. Possibly
3. Hope so. (then throw it away)
4. At 120,000 miles, yes.
That's what EPA stated.

 

Good question.
You need to be aware of your requirements. Not worth wasting a cat since they're so expensive.

 

These cars had catalytic converters with zdd in the oil for decades with no problem.

 

thanks for the feedback and opinions. as always motor oil is an endless topic.

 

You can order Valvoline VR1 at O'Reilly or Summit.
I think adding that bottle of ZDDPlus is too much zinc (zddp).

 

Let's talk some sense here!

The owners manual for a 68 C3 or even my 78 L-82 about oil recommendations is completely obsolete in today's world of synthetic oils. Back then, the conventional dyno oil was not even in the same league as are current base line "synthetic" oils in the USA. Be careful, though, since a synthetic oil in the ROW (rest of World) in most places is a true synthetic PAO ester Group IV derivative, not in the USA, where many "synthetic" oils are highly refined group IIIB conventional oils.The extremely high Zinc oil back 50 years ago augmented the lubrication of the conventional oils which was nothing like today's oils.

Either run a high zinc oil as others have suggested, 15W-50 Mobil 1 1200 PPM Zinc, for example, or my personal choice for every car I own and any power equipment I have from lawn tractor to snowblower to generac generator, new and old, Castrol or Mobil 1 European Formula Only, 0W-40, 1000/1100 PPM Zinc- Simply a superior mass market oil with incredible additive packages for excellent lubrication and extended oil Drain intervals, which does not apply to our cars. You want the oil thinner at startup and when colder, 0W, with superior film strength and viscosity index when hotter, 40 weight. The European Formula oils are outstanding versus standard Mass market oils...forget any mass market oils 10W-30, 40, 0W-20 etc which are mostly inferior to Specialty or Euro Formula oils

68 C3's do not have cats and my personal experience with 0W-40 European Formula oils is that they have NEVER poisoned the cats in any of my cars, NEVER. I just retired my 2001 Grand Prix with 240,000 miles on the OEM 3.1 motor (never burned an OZ of oil) and OEM tranny, lifetime of Mobil/Castrol 0W-40 Euro formula, with the OEM cat still going at 240,000 miles. My 2008 Chrysler 300 with 180,000 miles on the OEM motor also has used the same oils for its life and both cats still going strong. 10 C6Z06 has used 0W-40 since new, both cats are perfectly fine. I have never lost an engine or had one that burned oil, ever.

More government BS about the Zinc content and cats...give me a break!

 

But that was the whole point of the problem.
And that is exactly why the Gvmnt jumped in to ban Zinc.

The Feds wanted the cats to last 120,000.
The big three auto manufactures said, can't be done.
Why not? Asked the Feds.
We will test, get results and let you know, said the big three.
Later.
The Zinc is coating the internals of the cats. Thereby making them useless says the big three.
(Here is where the cat test pipe came in) No laws were enacted that stated how long you could leave the test pipe installed.

So, Zinc was banned for several yrs.
Little did we know why thousands upon thousands of camshafts / lifters were being destroyed.

Feds stepped in again. Ok, you can use zinc, but the bottle label must clearly state: For Off Road Use Only. (remember that?)

Today, after protests from us car guys, Zinc oils are easily available.

 

The real issue with the federal ban on zinc supposedly poisoning cats is that like almost everything else today, if 1/10th of 1% of all the cats made fail due to a Zinc issue, ban the product for any use by anyone. Total insanity..................the inmates have been running the asylum but not any more............cutesy time is over..........

 

I’m about to do the 78s first oil change since I had it. I have a ton of 20W50 ZR1 around. It’s the only thing that goes in my aircooled cars. They use 10.5 Litres per change… Was gonna use it but thought I’d check in over here. Seems like it’s popular here too.

Not sure if Lake Speed Jr is a house hold name over here in Vetteland. He is one of the only guys. I put my trust in with lubricants. I’ll attach a video, but search his vids, he’s what I’d call an expert.

 

The oil Geek guy. Yes his videos have been shared on here before.

 

I follow Lake Speed Jr.'s videos -- good information.
The VR1 is fine... and unless you do winter driving with the car the 20w-50 will be OK. If you're starting the engine below 0C then I'd be looking at a 10w-30.