I can understand that frame of mind, I was right there with you for more years than I care to admit to.
Pennzoil did used to use a base that caused sludge in motors but that hasn't been the case in over 20 years since they switched to a new non-paraffin base called PureBase for their conventionals. Their synthetics have never had that issue.
I used to believe the same thing on Fram, some obviously still do. What turned me around was a 2 day trip to Fram's R&D and testing labs in Dayton Ohio. This is what I wrote about it after coming home, please read it.
https://wranglertjforum.com/threads...it-to-frams-r-d-facility-in-dayton-ohio.9042/
I learned a lot on that trip, that is for sure... mainly that there's so much bullshit being spread on the internet that you have to take the negatives with a grain of salt. And that Fram's Tough Guard filter is such a good filter that I switched to that filter for all of my cars and Jeeps. It actually outperforms many filters costing 2-3X as much. For example, its filtration efficiency tests at 99%, many of the high-zoot filters only have a 95% filtration efficiency.
I still have a photo in my collection of photos that I kept labeled as-is to remind me of what I used to think about Fram lol.
View attachment 206517