hy-lube on 1990 Toyota Land Cruiser

last time i changed oil put in a bottle of hyper-lube do iput another next change ??

Asked by for the 1990 Toyota Land Cruiser
Toyota as a manufacture do not recommend the use of any oil additives or modifiers. I have no experience with Hyper lube additives I would send them an email or look for recommendations on there website.
I see the additive on there web page that is a Zinc additive, this definitely should not be used in your Toyota as it damages catalytic converters. ZDDP was taken out of oils to maintain cat convt life.
I wanted to post on this comment. This additive manufactured by Hyper-lube is actually a Zinc Replacement and does not contain Zinc or other heavy metals and will not harm the Catalytic converter as advertised on their website. (Hy-Per Lube Zinc Replacement Additive contains an exclusive Polymer Ester formula which, when added to any motor oil, including the new SM rated oils, will provide up to TWICE the EP wear protection as high content ZDDP motor oils and is also safe for use in all engines even those with catalytic converters)I have used their additives before and have noticed a smoother and quieter engine. I personally have not had any problems from using Hyper-lube.