Mk1 tappet / noise oil additives

[tonymor]

My mk1 developed a noisy tappet sound earlier last year and I was reckomended an oil additive on this forum which I added and it lubricated it very well.
My son is using the car now infrequently and I believe he's finding it doing similar and tappets are evident at higher revs .
I can't recall which additive I used so asking here for recommendations?
Thanks in advance.

[anonymous-user]

Wynns hydraulic lifter treatment.

https://www.ebay.co.uk/p/Wynns-76864-Hydraulic-Val...