cossie noisy tappets after rebuild - could it be the oil?

[john_p_b]

following on from yesterday where some of you kind ppl were telling me not to worry too much about my tappets tapping away, i'm wondering if the oil could have anything to do with it? car has always been run on mobil 1 15/50 and never made a noise out of place, now i've rebuilt it and it's tapping but i'm only running a 10/40 semi synthetic to run it in for a couple of hundred miles. oil pressure is crack on from cold on the new high pressure pump i fitted, runs at around 75-80psi @ 1500rpm then at normal cruising around 2500rpm when hot it sits at around 45-50psi. however when it's really hot and sitting at tickover the oil pressure is down to around 25psi which i can't help but feel is far too low and could be down to the oil being to thin at high temps? i've done 30 miles in it now and will put another 20 on it today, i've got a can of millers cfs 10/60 sat in the garage would it be worth me putting that in over the weekend or is it too soon and too thick anyway?

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[LHD220Turbo]

running in should be done on mineral oil, not semi

but you've not done enough miles!! - tappets sometimes take a few thousand to quieten down completely

cold oil pressure shows you havent got a oil pressure problem, so i wouldnt worry too much about the hot oil pressure - as you already know the oil weight & oil temp has an impact on oil pressure

[john_p_b]

i spoke to a few people about using mineral oil to run it in on and the popular opinion was mineral oil has in most cases caused more problems than anything else as it's no good for the turbo?

i figured using a semi will at worst just make it take longer to run in? if i'm seriously wrong i'll go drop it now and get some mineral oil.

[tabetha]

Mineral will be fine for the turbo as you are not thrashing it, so long as it is the best mineral you get, ie a well known brand.
I run in for around 1000 miles, but by 500 miles it has full throttle for brief periods, ie high rpm low loads in lower gears, don't run in too easy or the bores can glaze, I put in fresh mineral at 500 miles, 1500 miles, then 2000 miles, then fully synth.
tabetha

[john_p_b]

ok so what's a good mineral to get? and where from? will any decent motor factors do it? will the oil i'm using do me any harm? could it be contributing to the tappets being noisy?