Hello everyone!
I need your help. I have 1992 Audi 100S with 2.8L V6 12V with engine noise problem. This only occurs on cold start-up or when car sits for a long time (i.e. over the weekend); it sounds like valve/lifter tapping (after warm-up it goes away; oil pressure very good too). So I did some research and it sounds to me that I have bad oil check valves in engine valley and heads. I cannot find any aftermarket vendor that has them in stock, is this a dealer item? I hope not, lol. Can anyone help?
Thanks, Adis
P.S. Car had 102K miles on it.

102K ye probably lifetes. use syntetic and go one value below 15W use 10W etc...

the ifamous hydraulic valve lifters

maybe its time for an engine flush?

engine flush is a myth ... used by bad mechanics to scam you out of money

when my valves start ciking, i add a bit of auto tranny fluid to oil, and that flushes it good and stops the ticking.

I think I had the same problem ('93 audi 90s). It was actually the water pump bearing, but I started noticing leaks after a month or two.

I took her to AutoZone and the guy said: "It sound like a normal BMW motor!" :D...wtf?

you can use tranny oil to flush the engine, but that wont help the lifters, the oil will not clean out the lifters. Nothing does. I use 0w-40 and that keeps my lifters quit, even on cold days, I will hear 2 3 clicks and its gone. thats after parked for a week.

totally agree with KaKarot there 0W/40:)

thanks avant80, I did reasearch, large reaserach. the 0w40 will behave same as 10w-40 or 5w-40. it just has better cold behavior that any other I saw. Thank you mobil, dont screw up.
You can see my research, if you click on the link in my sig, and on the bottom of the page click "Oil" thats all, read on like 5 or 7 pages long :)

yep did that research 10 years ago when things were in the change from standard oils to synthetic ( man made ) that's why I changed to 0W/40 because hydraulic lifters benefit from it + the engine;)

I call it speed feed:)