Changing the viscosity of the oil from the manufacturer spec is only masking the problem. It also will increase wear or decrease oiling capability. It can also damage the oil pump.
Lifter noise is usually caused by lack of oil flow to the hydraulic lifters or excessive valve train wear.
Lucas oil stabilizer is not a good thing to use, all it does is change the viscosity of the oil when cold. Which will increase engine wear, namely bearings on start up, when the engine oil is crucial.
The ATF idea could work, the oil passage in the lifter itself could be clogged. Try it, if not you may have damaged lifters or another issue.
85 325 - 2.8 PTE6262 VEMS.