Q: Should I purchase non serviceable ball joints? 1995 lexus ls400 lower ball joint

The distinction of more relevance in purchasing a part such as a ball joint is "should one install the OEM (Lexus) part versus an aftermarket part?" If you want a long lasting ball joint that is guaranteed to fit your application, and be suitable in all respects, buy the part from the dealer. As far as serviceable versus non serviceable joints in the aftermarket, although again the "distinction" is truly a moot issue if the goal is installing the OPTIMUM part, I would need more information as to the vendor of the two "choices" and I would need to see the parts and also question the vendor about their design before I could say anything even remotely intelligent. Notably, just because a ball joint is "serviceable" (greaseable) does not mean it’s not a piece of junk. The non serviceable joint (the OEM joint is permanently greased, by the way) may very well be better than the serviceable one. At any rate, as indicated, it’s a moot issue. If you have a concern with parts (and you should) and are interested in performing these kinds of comparisons, I can tell you that in 100% of the cases, the OEM dealer supplied part is the only one that is actually guaranteed to fit and perform as intended by the original vehicle manufacturer. If you desire that a mechanic look at the particular parts of interest and make a further evaluation and/or simply procure and install the OEM part for you, please request service/inspection for suspension repairs and the responding certified mechanic will fully address all of your concerns. If you have further questions, do not hesitate to re-contact YourMechanic because we want you to make the most of your repair dollars and help you to get the best possible results.