Zinc
 

I have 2 LT1 cars. The first car (72k miles) has a stock roller cam witch needs no zinc oil additive. But the push rods showed lots of wear. Due to the lack of using a ware additive in the oil.
The 2nd. LT1 car (74k miles) the previous owner had used a oil with zinc (additive) in the oil and the push rods showed no noticeable ware. So, there are still a lot of engine parts that need a oil additive for reducing engine ware.
See photo.
There are some oils that have zinc additives.
Amsoil.
Red line.
Multi-grade racing oils.
Multi-grade diesel oils.
Mobil One diesel oils.
Or the oil I like "Convoy" engine oil with Moly.

had 200k miles on my first 93, as far as i know it never had additive, i know for sure the last 100k it did not. push rods looked fine.

I think you have other problems then zinc. Anything you run now with a roller cam is covered with the oils on the shelf. Flat tappet cams are a different story.

What Crabby and Yav8 said. Along with that, all oils still have zinc in them, and enough to protect 99 percent of the cars out there. Also, any engine oil you find that is API SL/SM/SN certified, racing or not, is restricted on the amount of ZDDP in it. Those that warn against use in modern engines due to possible catalytic converter damage and are not API certified, are not restricted.

No problems with the engine. I now have another 70,000 miles (I change the oil every 20k) on the car, push rods are just fine and no problems with the aluminum full rollers rockers. You should also use a magnetic oil drain plug. You'll be amazed on what shows up there.
I'm using 4qts of Mobil One 5w 30w and 1qt of Convoy moly oil with a 4 micron oil filter.
Gm has changed some of there oil filter from a 24 micron filter to a 12 micron filter and said it will reduce the engine ware by 85%. But you should know this, right.

If you change oil every 20K miles, as you posted, your engine is going to have more problems than just beat up pushrods. lol

The logistical problem with a 4 micron filter is that the carbon contained in the blow by is mostly larger than 4 microns. The larger paper filter only catch a small percentage of the fine carbon blow by so a 4 micron filter is great for the oil but terrible for the filter life. On an older motor with excessive blow by the filter can become plugged 4-5000 miles. Once the filter plugs up the bypass opens and you are using unfiltered oil.
You are not the first people I know that subscribes to using synthetic for a lot of miles. You just forgot to mention changing the filter every 5-7000 miles. I agree the 4 micron filter is a good idea but you really do not want to try to get 20k out of it. I use Mobil 1 oil and a Mobil 1 filter (which is 3-5 micron filter) and I change oil every 5-7000 miles on a motor with 135,000 miles on it. My 5.3 in my SUV gets it every 3-4000 miles because it does a lot of in town driving and some towing.

Just a FYI if you use just the Mobil 1 your engine is not going to fail due to an oil problem. In fact very few engines fail due to an oil issue. Unlike in the 70’s most cars that go to the junk yard do so with a motor still running fine. It is not uncommon to see cars these days with 275K on the clock being driven to the junk yard because they need $1200 worth of brakes and suspension work to pass inspection and that car is not worth fixing or it is towed in with a bad transmission.

Most engine failure that do occurs because of some other failure, a stuck thermostat, fans not working, a failed water pump or some other coolant leak causes the motor to overheat. The head bolt get stretched and the piston grows too large for the cylinder and that is what damages the motor. You heat up your motor up to 270 degs and it is not going to matter what oil you have. Blown head gasket is the LT1 killer. People should really get under their car 3-4 times a year and check the water pump weep hole and track the hoses looking for small leaks. I do this every oil change. I have never had a surprise on the highway with my coolant system. Every water pump I have ever changed on my cars has been because of a drop of coolant coming out of the weep hole found during an oil change.

90% of the time a 4 micron filter with a oil with good detergent will fix a GM lifter tap. 3-4 micron is as low as you can really go because after that you will start to filter out some of the oil additives.

first of all no matter what you say gorn it allways makes sence .to me,with my blown head gasket I tend to think age of the gaskets played a role .loose bolts ,but as well that I changed the oil at 5000,when mine went I was doing a burnout the water light came on I thought nothing of it ,little did I know when it blew its in slow fashion adding water I thought was all I needed hot in summer ,meening it took time to notice the fans not comeing on when they should have minor overheating,an the anti freeze smoke from the cans,there not bullet proof ,zinc factor only comes in with flat tappit lifters an cams 89 an earlier engines ,they say some can use more zinc ,but o2 sensors an cats don't like it ,so for a breakin on new engines yes ,full time no,my engine yes couse its flat tappit,to me the thing that makes them tough ,is that I drove it for near a year with a blown head gasket with no water in the oil ,then the pump went 2 times in 6 months weep hole thing ,so what gorn said he knows,at that point every seal I had was leaking slowly ,oil pan manifold head ,I guess had I not had to hot rod the car one to many times it probley would have made 150.000 miles ,had I drove it normal,but time plays a role to I think ,anyone with al original seals with 80.000+an 15 to 20 years old . is takeing there chances ,like I would not buy an 1995 pace car couse it was garage kept for 20 years ,with 20.000 miles for $15000 ,couse chances are the seals gaskets are getting brittle,an the odds of it seeing 100.000 miles without all new seals gaskets hoses ,I would not take the chances ,now at $5000.00 si.I also read that 4 microns to 20 microns is a misconception,i am running a k&n filter 20 microns good to 10,000 miles,but I will change it at 3 ,then go the fram extra guard ,same 20 micron rateing 3000 to 5000,so lower is not better ,do some research,with oil an filter there will always be so many different opions,I started with wix most 10 microns k&n 20 fram 3x 20 microns ,so it like oils we can argue wich one is best all day

So, you ran the car low on water, overheated and blew a head gasket. Nothing new in that, it happens all the time when you don't pay attention to the signals the engine is sending out. lol As for flat tappets, the main thing is breaking them in properly with the right type of lubricants. After that, unless you have a monster cam with monster springs, a synthetic like Mobil 1 will work fine as long as it is replaced when dirty and starts regrinding the cam lobes.

Its funny, I have read so much about people opinions on how to break in a Cam. There was a time in my life when I was putting together a lot of engines. I had one simple rule. Follow the break in process given by the Cam manufacture that came in the box with the Cam. I never had an issue and never really thought about it farther then that.

Head gasket failure almost always comes back to the car not being maintained. Either the coolant is not changed every 3-4 year, the coolant breaks down and forms a acid that eats away and gaskets and aluminum or the car overheats and causes the head bolts to stretch.