Adding Zinc to Oil?

[tirod]

According to the API information I read - they use a Chevy and Toyota flat tappet motor as part of the SM (now SN) certification. Again - read the latest spec, and as already said by others, they reduced the zinc - not eliminated it. I'm certainly not saying engines didn't fail - but engine builders aren't forensic scientists, and don't make a living examining blown motors. They build them and let others do that.

It's been a long term issue for decades, newly started motors scuff lifters, and lobes fail. Engine assembly lube generously used on high stress engine parts has been recommended for a long time. I doubt these guys suddenly all stopped using it - so what else could account for a significant number of lifters failing if the engines were using oil with SOME zinc and assembly lube, too?

There's other friction points, the reduced zinc hasn't affected rockers, valves, piston pins, or skirts - in flat tappet OR roller tappet motors. Those other friction points haven't changed.

I hearing a lot of "Blame the zinc" when it was the lifters all along. And the guys who imported them took a big hit in business back then, too. Those in the know quit buying. There's a lot more to it than zinc, but it's easy to blame. And it makes some people a lot of money to sell that zinc!