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Being an NA6 (or NA8) it could be HLA noise, but usually it disipates after a while & then returns.

Many forumites have had excellent results using Nulon Lifter Free. Sometimes an oil change or different oil grade can also help. Could also be something other than HLA noise, but not easy to diagnose remotely with limited info.

HLA noise: search.php?keywords=hla+noise&terms=all&author=&sc=1&sf=all&sk=t&sd=d&sr=posts&st=0&ch=300&t=0&submit=Search

OP says noise is present when engine is cold and hot.

Is it really a ticking noise, or a tapping noise?

Apu wrote:OP says noise is present when engine is cold and hot.

blk na6 wrote:...and it's also there while cold and warm...

I've heard HLA noise in NA6 or NA8 when cold, warm or hot. With a bit of continued drving it sometimes stops making the noise, to usually return another day.

Sounds like the Hydraulic Lifter Assemblies.

Nothing to stress about.

Replace them rather than use chemicals and oils to try to mask them. They can be had for 120 odd for the set.

Dann

In case you're tempted to go for the middle option of cleaning HLAs as per:
http://www.miata.net/garage/hla/cleaning.html
Don't bother, as it's time consuming & doesn't necessarily give the result hoped for:
viewtopic.php?f=29&t=41116&p=529002&hilit=hla+cleaning#p529002

blk na6 wrote:I might give it a go now after I get my headlights flush, gave it a quick read looks simple

Don't waste you're time cleaning them - either replace them or go the chemically enhanced option!