Old wives tale and complete nonsense.
The story started because some old Big Block Chevys didn't like it. Long and boring story.
Today's machining process is far advanced from the 60's. Switch back and forth as mush as you want. Personally, I wouldn't bother. Just use a good syn and head on down the road. If you need to top it off with some dino oil, go for it. Just try to use the same weight, if possible. Even then, it's not the end of the world.
Oh, yes I was the proud owner of a 1974 Caprice Classic with a 454 cu inch engine. Every one thousand miles, open the hood and pour in a quart. Being driving along and a lifter would collapse.
The first time it happen I pulled into a full service, service Station (those days are long gone) A young gentleman came out and asked what I needed and I asked him if he had any idea about what the noise was. He raised the hood, pulled a screwdriver out of his pocket leaned over and placed it on the right valve cover. Raised back up and said a lifter has collapsed on the right bank, happens with the 454 because of the strong valve spring pressure. Since the vehicle only had 3,000 miles on it I took it back to the Dealer the next morning for warranty repair.
Now the good part. Upon arriving at the Dealership Service Department I was asked what i was bringing the vehicle in for. I told him a lifter on the right side of the engine had collapsed. He looked at me like I had three heads and grunted.
I left the vehicle and after not hearing anything for two days I called the Service Department. I got the reply of we are looking at the vehicle and trying to determine where the noise is coming from. I told the person a lifter on the right side of the engine has collapsed, again I got a grunt. Long story short I would call ever two days for a week and a half and get the same answer. Having enough of that I asked to speak to the manager. I asked him to provide me with a definitive date my vehicle would be ready and told him that I had also called Chevrolet and asked for the vehicle to be transferred to the other Chevrolet Dealership in town for the warranty repairs.
He advised he was going to check into the problem. The next morning he called back and advised he had great news. He advised the service department had finally determined what the noise was. A lifer on the right side of the engine had collapsed. I asked him to read off of the warranty repair request I made when presenting the vehicle for service. He said, d**n lifter on right side collapsed and hung up.
I called Chevrolet again. A area representative called me back in about thirty minutes and advised he was in route to the dealership and my vehicle would be ready for pickup by 3 pm. At 3pm when I went to pick the vehicle up everyone was apologetic. I told them I was not in the mood to hear it, retrieved my vehicle and left.
I traded the vehicle two years later after having other problems with it and always wondered if the problems being experienced were sleeper problems left by the Dealer Service Department for me to experience on some dark rainy cold night.
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